test(canvas): add ActivityTab and MissingKeysModal component tests
- ActivityTab.test.tsx: 27 tests covering filter bar (aria-pressed states,
API reload), loading/error/empty states, ActivityRow content (type badges,
method, duration_ms, summary, error styling), A2A flow indicators,
auto-refresh Live/Paused toggle, refresh button, activity count
- MissingKeysModal.component.test.tsx: 25 tests covering visibility,
ARIA semantics (role=dialog, aria-modal, aria-labelledby), content,
keyboard (Escape, Enter), save flow (disabled/.../Saved/error), Add Keys
& Deploy gate, Cancel + backdrop click, Open Settings button
- MissingKeysModal.test.tsx: refactored to preflight logic only (7 tests);
component rendering now covered in component test file
863 tests passing (+3 net).
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>