fix(web): resolve flaky CI test failures in LinkAutocomplete and FilterBar

- LinkAutocomplete: use refs for event handler state to prevent stale
  closures when effect re-attachment is delayed in slower CI environments
- FilterBar: increase debounce test timeout from 100ms to 500ms to
  prevent premature timer firing during userEvent.type in CI

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

apps/web/src/components/filters/FilterBar.test.tsx

@@ -46,8 +46,8 @@ describe("FilterBar", (): void => {
   it("should debounce search input", async (): Promise<void> => {
     const user = userEvent.setup();
 
-    // Use a very short debounce to test the behavior without flaky timing
-    render(<FilterBar onFilterChange={mockOnFilterChange} debounceMs={100} />);
+    // Use a debounce long enough that CI environments don't fire it between keystrokes
+    render(<FilterBar onFilterChange={mockOnFilterChange} debounceMs={500} />);
 
     const searchInput = screen.getByPlaceholderText(/search/i);
     mockOnFilterChange.mockClear();
@@ -71,7 +71,7 @@ describe("FilterBar", (): void => {
           expect.objectContaining({ search: "test" })
         );
       },
-      { timeout: 200 }
+      { timeout: 1000 }
     );
 
     // Verify it was only called once (debounced)