refactor(types): rename AppType to AppId for semantic clarity

Rename `AppType` to `AppId` across the entire frontend codebase to better
reflect its purpose as an application identifier rather than a type category.
This aligns frontend naming with backend command parameter conventions.

Changes:
- Rename type `AppType` to `AppId` in src/lib/api/types.ts
- Remove `AppType` export from src/lib/api/index.ts
- Update all component props from `appType` to `appId` (43 files)
- Update all variable names from `appType` to `appId`
- Synchronize documentation (CHANGELOG, refactoring plans)
- Update test files and MSW mocks

BREAKING CHANGE: `AppType` type is no longer exported. Use `AppId` instead.
All component props have been renamed from `appType` to `appId`.

src/lib/api/settings.ts

@@ -1,6 +1,6 @@
 import { invoke } from "@tauri-apps/api/core";
 import type { Settings } from "@/types";
-import type { AppType } from "./types";
+import type { AppId } from "./types";
 
 export interface ConfigTransferResult {
   success: boolean;
@@ -30,12 +30,12 @@ export const settingsApi = {
     return await invoke("is_portable_mode");
   },
 
-  async getConfigDir(appType: AppType): Promise<string> {
-    return await invoke("get_config_dir", { app: appType });
+  async getConfigDir(appId: AppId): Promise<string> {
+    return await invoke("get_config_dir", { app: appId });
   },
 
-  async openConfigFolder(appType: AppType): Promise<void> {
-    await invoke("open_config_folder", { app: appType });
+  async openConfigFolder(appId: AppId): Promise<void> {
+    await invoke("open_config_folder", { app: appId });
   },
 
   async selectConfigDirectory(defaultPath?: string): Promise<string | null> {