Chat search (#1224)

Based on https://github.com/dyad-sh/dyad/pull/1116
    
<!-- This is an auto-generated description by cubic. -->
---

## Summary by cubic
Adds a fast chat search dialog (Command Palette) to find and jump
between chats. Open via the sidebar button or Ctrl/Cmd+K, with title and
message text search plus inline snippets.

- New Features
  - Command palette using cmdk with keyboard shortcut (Ctrl/Cmd+K).
- Searches within the selected app across chat titles and message
content via a new IPC route (search-chats).
- Debounced queries (150ms) with React Query; results de-duplicated and
sorted by newest.
- Snippet preview with highlighted matches and custom ranking; selecting
a result navigates and closes the dialog.
- Search button added to ChatList; basic e2e tests added (currently
skipped).

- Dependencies
  - Added cmdk@1.1.1.
- Bumped @radix-ui/react-dialog to ^1.1.15 and updated Dialog to support
an optional close button.

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

---------

Co-authored-by: Evans Obeng <iamevansobeng@outlook.com>
Co-authored-by: Evans Obeng <60653146+iamevansobeng@users.noreply.github.com>

src/ipc/ipc_client.ts

@@ -4,6 +4,7 @@ import {
   ChatSummariesSchema,
   type UserSettings,
   type ContextPathResults,
+  ChatSearchResultsSchema,
 } from "../lib/schemas";
 import type {
   AppOutput,
@@ -63,7 +64,11 @@ import type {
   UpdatePromptParamsDto,
 } from "./ipc_types";
 import type { Template } from "../shared/templates";
-import type { AppChatContext, ProposalResult } from "@/lib/schemas";
+import type {
+  AppChatContext,
+  ChatSearchResult,
+  ProposalResult,
+} from "@/lib/schemas";
 import { showError } from "@/lib/toast";
 
 export interface ChatStreamCallbacks {
@@ -288,6 +293,20 @@ export class IpcClient {
     }
   }
 
+  // search for chats
+  public async searchChats(
+    appId: number,
+    query: string,
+  ): Promise<ChatSearchResult[]> {
+    try {
+      const data = await this.ipcRenderer.invoke("search-chats", appId, query);
+      return ChatSearchResultsSchema.parse(data);
+    } catch (error) {
+      showError(error);
+      throw error;
+    }
+  }
+
   // Get all apps
   public async listApps(): Promise<ListAppsResponse> {
     return this.ipcRenderer.invoke("list-apps");