feat(FN-1260): add full-text search for tasks and comments

- Add FTS5 virtual table with v21 database migration for task search
- Add searchTasks() method to TaskStore with FTS5 query support
- Add q= search parameter to GET /api/tasks route for server-side search
- Update useTasks hook and frontend API to support searchQuery prop
- Update Board.tsx and App.tsx to pass searchQuery through component hierarchy
- Add comprehensive tests for FTS5 index and searchTasks functionality

packages/dashboard/app/api.ts

@@ -93,11 +93,12 @@ async function api<T = unknown>(path: string, opts: RequestInit = {}): Promise<T
   return data as T;
 }
 
-export function fetchTasks(limit?: number, offset?: number, projectId?: string): Promise<Task[]> {
+export function fetchTasks(limit?: number, offset?: number, projectId?: string, q?: string): Promise<Task[]> {
   const search = new URLSearchParams();
   if (limit !== undefined) search.set("limit", String(limit));
   if (offset !== undefined) search.set("offset", String(offset));
   if (projectId) search.set("projectId", projectId);
+  if (q) search.set("q", q);
   const suffix = search.size > 0 ? `?${search.toString()}` : "";
   return api<Task[]>(`/tasks${suffix}`);
 }