migrate signup page to composition API and typescript

src/lib/common.ts

@@ -1,3 +1,5 @@
+import type { TypeAndDisplayName } from '@/core/base.ts';
+
 // eslint-disable-next-line @typescript-eslint/no-unsafe-function-type
 export function isFunction(val: unknown): val is Function {
     return typeof(val) === 'function';
@@ -310,6 +312,16 @@ export function getItemByKeyValue<T>(src: Record<string, T>[] | Record<string, R
     return null;
 }
 
+export function findDisplayNameByType(items: TypeAndDisplayName[], type: number): string | null {
+    for (const item of items) {
+        if (item.type === type) {
+            return item.displayName;
+        }
+    }
+
+    return null;
+}
+
 export function getNameByKeyValue<V, N>(src: Record<string, N | V>[] | Record<string, Record<string, N | V>>, value: V, keyField: string | null, nameField: string, defaultName?: N): N | undefined {
     if (isArray(src)) {
         const arr = src as Record<string, N | V>[];