feat: Add remote sync for project clones

Fetch remote changes before agents start working so they build on
up-to-date code. Adds ProjectSyncManager with git fetch + ff-only
merge of defaultBranch, integrated into phase dispatch to sync
before branch creation.

- Schema: lastFetchedAt column on projects table (migration 0029)
- Events: project:synced, project:sync_failed
- Phase dispatch: sync all linked projects before creating branches
- tRPC: syncProject, syncAllProjects, getProjectSyncStatus
- CLI: cw project sync [name] --all, cw project status [name]
- Frontend: sync button + ahead/behind badge on projects settings

docs/dispatch-events.md

@@ -27,6 +27,7 @@
 | **Preview** | `preview:building`, `preview:ready`, `preview:stopped`, `preview:failed` | 4 |
 | **Conversation** | `conversation:created`, `conversation:answered` | 2 | `conversation:created` triggers auto-resume of idle target agents via `resumeForConversation()` |
 | **Chat** | `chat:message_created`, `chat:session_closed` | 2 | Chat session lifecycle events |
+| **Project** | `project:synced`, `project:sync_failed` | 2 | Remote sync results from `ProjectSyncManager` |
 | **Log** | `log:entry` | 1 |
 
 ### Key Event Payloads