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/server-api.md

@@ -162,6 +162,9 @@ Each procedure uses `require*Repository(ctx)` helpers that throw `TRPCError(INTE
 | deleteProject | mutation | Delete clone and record |
 | getInitiativeProjects | query | Projects for initiative |
 | updateInitiativeProjects | mutation | Sync junction table |
+| syncProject | mutation | `git fetch` + ff-only merge of defaultBranch, updates `lastFetchedAt` |
+| syncAllProjects | mutation | Sync all registered projects |
+| getProjectSyncStatus | query | Returns `{ ahead, behind, lastFetchedAt }` for a project |
 
 ### Pages
 | Procedure | Type | Description |