Implementing app search feature (#1302)

This PR implements app search feature and addresses the issue #1182.
    
<!-- This is an auto-generated description by cubic. -->
---

## Summary by cubic
Adds a fast app search with a command-style dialog so users can find
apps by name or chat content and jump to them quickly. Implements the
search experience requested in #1182.

- New Features
- Search dialog (Ctrl+K or “Search Apps” button) with result snippets
from matching chat titles/messages.
- Searches across app names, chat titles, and message content;
case-insensitive; supports partial matches; empty query lists all apps.
  - Selecting a result navigates to the app and closes the dialog.
- New IPC endpoint search-app with Zod-validated results, debounced
React Query hook, and preload allowlist update.
- Added E2E tests for dialog open/close, shortcuts, matching behavior,
empty state, and navigation.

<!-- End of auto-generated description by cubic. -->

src/hooks/useSearchApps.ts

@@ -0,0 +1,22 @@
+import { IpcClient } from "@/ipc/ipc_client";
+import { AppSearchResult } from "@/lib/schemas";
+import { keepPreviousData, useQuery } from "@tanstack/react-query";
+
+export function useSearchApps(query: string) {
+  const enabled = Boolean(query && query.trim().length > 0);
+
+  const { data, isFetching, isLoading } = useQuery({
+    queryKey: ["search-apps", query],
+    enabled,
+    queryFn: async (): Promise<AppSearchResult[]> => {
+      return IpcClient.getInstance().searchApps(query);
+    },
+    placeholderData: keepPreviousData,
+    retry: 0,
+  });
+
+  return {
+    apps: data ?? [],
+    loading: enabled ? isFetching || isLoading : false,
+  };
+}