Phase 1 of message feedback is now included (issue #18).

New features:
- Added nullable `rating` on `copilot_messages` (`positive` / `negative` / `null`) with thumbs up/down under assistant messages.
- Users can set or clear ratings with a second click.
- `CopilotChat::submitRating()` now re-resolves message scope first (panel/participant/tenant), validates rating, and safely no-ops unauthorized access.
- `ConversationManager::getMessagesForChat()` now returns message `id` and `rating`.
- Streaming now returns the persisted assistant `messageId` in SSE `done`, enabling exact rating of the just-streamed reply.
- Backward compatibility preserved for older published chat views.
- Management UI now includes a Thumbs Down badge and a "Has Negative Rating" ternary filter.
- Feature is controlled by `filament-copilot.feedback.enabled` (default `true`).
- Added translation strings and new tests (all green).

Thanks to @Apollo139 for the contribution in PR #21.