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/lib/schemas.ts

@@ -44,6 +44,20 @@ export type ChatSearchResult = z.infer<typeof ChatSearchResultSchema>;
 
 export const ChatSearchResultsSchema = z.array(ChatSearchResultSchema);
 
+// Zod schema for app search result objects returned by the search-app IPC
+export const AppSearchResultSchema = z.object({
+  id: z.number(),
+  name: z.string(),
+  createdAt: z.date(),
+  matchedChatTitle: z.string().nullable(),
+  matchedChatMessage: z.string().nullable(),
+});
+
+// Type derived from AppSearchResultSchema
+export type AppSearchResult = z.infer<typeof AppSearchResultSchema>;
+
+export const AppSearchResultsSchema = z.array(AppSearchResultSchema);
+
 const providers = [
   "openai",
   "anthropic",