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/hooks/useSettings.ts

@@ -1,7 +1,7 @@
 import { useCallback, useMemo } from "react";
 import { useTranslation } from "react-i18next";
 import { toast } from "sonner";
-import { settingsApi, type AppType } from "@/lib/api";
+import { settingsApi, type AppId } from "@/lib/api";
 import { useSettingsQuery, useSaveSettingsMutation } from "@/lib/query";
 import type { Settings } from "@/types";
 import { useSettingsForm, type SettingsFormState } from "./useSettingsForm";
@@ -26,11 +26,11 @@ export interface UseSettingsResult {
   resolvedDirs: ResolvedDirectories;
   requiresRestart: boolean;
   updateSettings: (updates: Partial<SettingsFormState>) => void;
-  updateDirectory: (app: AppType, value?: string) => void;
+  updateDirectory: (app: AppId, value?: string) => void;
   updateAppConfigDir: (value?: string) => void;
-  browseDirectory: (app: AppType) => Promise<void>;
+  browseDirectory: (app: AppId) => Promise<void>;
   browseAppConfigDir: () => Promise<void>;
-  resetDirectory: (app: AppType) => Promise<void>;
+  resetDirectory: (app: AppId) => Promise<void>;
   resetAppConfigDir: () => Promise<void>;
   saveSettings: () => Promise<SaveResult | null>;
   resetSettings: () => void;