fix(numpad): 全部按键 @click 换 @pointerdown.left，零延迟

第一阶段（touch-action: manipulation）只解了浏览器双击缩放延迟，但 F7
内部 tap 合成 + active-state 检测仍让 @click 比 pointerdown 慢一拍。
完全弃用 @click：

- 16 个按键（数字 0-9、运算 ×−+、C 清空、小数点/双零、OK 确认）改 @pointerdown.left
- 触屏 button=0 始终满足 .left 修饰符
- 桌面右键 button=2 不会误触发
- F7 active-state 视觉反馈基于独立 touchstart/touchend 监听，按下效果保留
- 退格键的 pointer 事件方案在上个 commit 已实现，本次不动

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

FORK.md

@@ -84,7 +84,8 @@
   1     2     3      +
   C     0     .     OK
 ```
-- ⌫ 单击退格，长按清除；C 清除全部
+- ⌫ 单击退格；按住不放先删一位、约 500ms 后清空全部（长按响应细节见 #11 第二阶段）
+- C 一键清除全部
 - 涉及文件：`src/components/mobile/NumberPadSheet.vue`
 
 ---
@@ -136,17 +137,24 @@
 - Tab 切换动画保持原样（设置中已有开关可控制）
 - 涉及文件：`src/styles/mobile/global.scss`
 
-### 11. 🟢 小键盘点击卡顿（修正：范围非全局）
+### 11. 🟢 小键盘点击卡顿（三次修正）
-**描述：** 移动端点击按钮有延迟感。
+**描述：** 移动端小键盘点击有延迟感。
 
-**真因（2026-05-02 定位）：** **不是**全局点击/接口响应问题。诊断后确认仅小键盘有卡顿，其他按钮正常。根因是上游在 `.numpad-button` 上设了 `touch-action: none`（commit `e178a079` "code refactor" by MaysWind），与 F7 内部 tap 处理叠加后让 click 事件合成慢一拍。backspace（个人新增 `.numpad-backspace-button` 类）不受影响，刚好佐证范围。
+**第一阶段（2026-05-02）`touch-action: none` 引发的 300ms 双击延迟：** 上游在 `.numpad-button` 上设了 `touch-action: none`（commit `e178a079` "code refactor" by MaysWind），与浏览器双击缩放检测叠加后保留了老式 300ms 点击延迟。
+- 修复：`.numpad-button` 的 `touch-action: none` 改为 `touch-action: manipulation`（W3C 标准"快速点击"值，禁双击缩放）
 
-**已完成：**
+**第二阶段（2026-05-08）退格键 `@taphold` 等待 750ms：** backspace 单点仍可感知延迟。根因是 `@click` + `@taphold` 让 F7 必须等 ~750ms 判别 tap vs hold，期间 click 被抑制。
-- `.numpad-button` 的 `touch-action: none` 改为 `touch-action: manipulation`
+- 修复：弃用 `@click="backspace" @taphold="clear()"`，改为原生 `pointerdown`/`pointerup`/`pointercancel`/`pointerleave` + 自管定时器
-- `manipulation` 是 W3C 标准的"快速点击"值：禁双击缩放（消除老 300ms 延迟）但保留 click 事件正常合成
+- 行为：单击立即删一位；按住不放先删一位、约 500ms 后清空全部
-- 涉及文件：`src/components/mobile/NumberPadSheet.vue`
 
-**附带认知：** 原 #11 假设是"全局点击响应慢"或"接口慢"，与 #12 离线缓存挂钩调研。实际诊断后跟那两条都无关，纯 CSS `touch-action` 与框架 tap 处理叠加导致。该认知值得记录避免后续误诊路径。
+**第三阶段（2026-05-08）所有数字/运算键也延迟：** 第一阶段修完后用户反馈数字键仍有"等一拍"感。怀疑 F7 整套 tap 处理（含 active-state 检测、`fastClicks` 兼容代码、tap-hold 全局监听）即便不显式声明 `@taphold` 也会给 `@click` 加上判别期。
+- 修复：把所有按键（数字 0-9、运算 ×−+、C 清空、小数点/双零、OK 确认）的 `@click` 全部换成 `@pointerdown.left`
+- 原理：`pointerdown` 在按下瞬间触发，绕开 F7 的 tap 合成路径。`.left` 修饰符限制只响应主键（触屏 button=0 始终满足，桌面右键不会误触发）
+- F7 的 `.active-state` 视觉反馈基于独立的 touchstart/touchend 监听，不依赖 `@click`，按下视觉效果保留
+
+涉及文件：`src/components/mobile/NumberPadSheet.vue`
+
+**附带认知：** 原 #11 假设是"全局点击响应慢"或"接口慢"，与 #12 离线缓存挂钩调研。实际诊断后跟那两条都无关——纯 F7 框架 tap 合成 + 双击缩放 + taphold 检测三者叠加。最终通过完全弃用 `@click` 改 pointer 事件解决。该认知值得记录避免后续误诊路径。
 
 ---
 

src/components/mobile/NumberPadSheet.vue

@@ -8,7 +8,11 @@
             </div>
             <div class="numpad-values">
                 <span id="numpad-value" class="numpad-value" :class="currentDisplayNumClass" @click="onDisplayValueClick">{{ currentDisplay }}</span>
-                <f7-button class="numpad-backspace-button" @click="backspace" @taphold="clear()">
+                <f7-button class="numpad-backspace-button"
+                           @pointerdown="onBackspacePointerDown"
+                           @pointerup="onBackspacePointerEnd"
+                           @pointercancel="onBackspacePointerEnd"
+                           @pointerleave="onBackspacePointerEnd">
                     <f7-icon class="icon-with-direction" f7="delete_left"></f7-icon>
                 </f7-button>
             </div>
@@ -21,55 +25,55 @@
             </f7-popover>
 
             <div class="numpad-buttons">
-                <f7-button class="numpad-button numpad-button-num" @click="inputNum(7)">
+                <f7-button class="numpad-button numpad-button-num" @pointerdown.left="inputNum(7)">
                     <span class="numpad-button-text numpad-button-text-normal">{{ digits[7] }}</span>
                 </f7-button>
-                <f7-button class="numpad-button numpad-button-num" @click="inputNum(8)">
+                <f7-button class="numpad-button numpad-button-num" @pointerdown.left="inputNum(8)">
                     <span class="numpad-button-text numpad-button-text-normal">{{ digits[8] }}</span>
                 </f7-button>
-                <f7-button class="numpad-button numpad-button-num" @click="inputNum(9)">
+                <f7-button class="numpad-button numpad-button-num" @pointerdown.left="inputNum(9)">
                     <span class="numpad-button-text numpad-button-text-normal">{{ digits[9] }}</span>
                 </f7-button>
-                <f7-button class="numpad-button numpad-button-function no-right-border" @click="setSymbol('×')">
+                <f7-button class="numpad-button numpad-button-function no-right-border" @pointerdown.left="setSymbol('×')">
                     <span class="numpad-button-text numpad-button-text-normal">&times;</span>
                 </f7-button>
-                <f7-button class="numpad-button numpad-button-num" @click="inputNum(4)">
+                <f7-button class="numpad-button numpad-button-num" @pointerdown.left="inputNum(4)">
                     <span class="numpad-button-text numpad-button-text-normal">{{ digits[4] }}</span>
                 </f7-button>
-                <f7-button class="numpad-button numpad-button-num" @click="inputNum(5)">
+                <f7-button class="numpad-button numpad-button-num" @pointerdown.left="inputNum(5)">
                     <span class="numpad-button-text numpad-button-text-normal">{{ digits[5] }}</span>
                 </f7-button>
-                <f7-button class="numpad-button numpad-button-num" @click="inputNum(6)">
+                <f7-button class="numpad-button numpad-button-num" @pointerdown.left="inputNum(6)">
                     <span class="numpad-button-text numpad-button-text-normal">{{ digits[6] }}</span>
                 </f7-button>
-                <f7-button class="numpad-button numpad-button-function no-right-border" @click="setSymbol('−')">
+                <f7-button class="numpad-button numpad-button-function no-right-border" @pointerdown.left="setSymbol('−')">
                     <span class="numpad-button-text numpad-button-text-normal">&minus;</span>
                 </f7-button>
-                <f7-button class="numpad-button numpad-button-num" @click="inputNum(1)">
+                <f7-button class="numpad-button numpad-button-num" @pointerdown.left="inputNum(1)">
                     <span class="numpad-button-text numpad-button-text-normal">{{ digits[1] }}</span>
                 </f7-button>
-                <f7-button class="numpad-button numpad-button-num" @click="inputNum(2)">
+                <f7-button class="numpad-button numpad-button-num" @pointerdown.left="inputNum(2)">
                     <span class="numpad-button-text numpad-button-text-normal">{{ digits[2] }}</span>
                 </f7-button>
-                <f7-button class="numpad-button numpad-button-num" @click="inputNum(3)">
+                <f7-button class="numpad-button numpad-button-num" @pointerdown.left="inputNum(3)">
                     <span class="numpad-button-text numpad-button-text-normal">{{ digits[3] }}</span>
                 </f7-button>
-                <f7-button class="numpad-button numpad-button-function no-right-border" @click="setSymbol('+')">
+                <f7-button class="numpad-button numpad-button-function no-right-border" @pointerdown.left="setSymbol('+')">
                     <span class="numpad-button-text numpad-button-text-normal">&plus;</span>
                 </f7-button>
-                <f7-button class="numpad-button numpad-button-num" @click="clear()">
+                <f7-button class="numpad-button numpad-button-num" @pointerdown.left="clear()">
                     <span class="numpad-button-text numpad-button-text-normal">C</span>
                 </f7-button>
-                <f7-button class="numpad-button numpad-button-num" @click="inputNum(0)">
+                <f7-button class="numpad-button numpad-button-num" @pointerdown.left="inputNum(0)">
                     <span class="numpad-button-text numpad-button-text-normal">{{ digits[0] }}</span>
                 </f7-button>
-                <f7-button class="numpad-button numpad-button-num" v-if="supportDecimalSeparator" @click="inputDecimalSeparator()">
+                <f7-button class="numpad-button numpad-button-num" v-if="supportDecimalSeparator" @pointerdown.left="inputDecimalSeparator()">
                     <span class="numpad-button-text numpad-button-text-normal">{{ decimalSeparator }}</span>
                 </f7-button>
-                <f7-button class="numpad-button numpad-button-num" v-if="!supportDecimalSeparator" @click="inputDoubleNum(0)">
+                <f7-button class="numpad-button numpad-button-num" v-if="!supportDecimalSeparator" @pointerdown.left="inputDoubleNum(0)">
                     <span class="numpad-button-text numpad-button-text-normal">{{ `${digits[0]}${digits[0]}` }}</span>
                 </f7-button>
-                <f7-button class="numpad-button numpad-button-confirm no-right-border no-bottom-border" fill @click="confirm()">
+                <f7-button class="numpad-button numpad-button-confirm no-right-border no-bottom-border" fill @pointerdown.left="confirm()">
                     <span :class="{ 'numpad-button-text': true, 'numpad-button-text-confirm': !currentSymbol }">{{ confirmText }}</span>
                 </f7-button>
             </div>
@@ -326,6 +330,31 @@ function clear(): void {
     currentSymbol.value = '';
 }
 
+const BACKSPACE_HOLD_TO_CLEAR_MS = 500;
+let backspaceClearTimer: ReturnType<typeof setTimeout> | null = null;
+
+function onBackspacePointerDown(event: PointerEvent): void {
+    // 按下立刻删一位（消除 F7 taphold 判别期带来的点击延迟）
+    if (event.button !== undefined && event.button !== 0) {
+        return;
+    }
+    backspace();
+    if (backspaceClearTimer !== null) {
+        clearTimeout(backspaceClearTimer);
+    }
+    backspaceClearTimer = setTimeout(() => {
+        clear();
+        backspaceClearTimer = null;
+    }, BACKSPACE_HOLD_TO_CLEAR_MS);
+}
+
+function onBackspacePointerEnd(): void {
+    if (backspaceClearTimer !== null) {
+        clearTimeout(backspaceClearTimer);
+        backspaceClearTimer = null;
+    }
+}
+
 function paste(): void {
     showPastePopover.value = false;
 
@@ -442,6 +471,7 @@ function onSheetOpen(): void {
 }
 
 function onSheetClosed(): void {
+    onBackspacePointerEnd();
     close();
 }