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/database.md

@@ -124,6 +124,7 @@ All adapters use nanoid() for IDs, auto-manage timestamps, and use Drizzle's `.r
 | name | text NOT NULL UNIQUE | |
 | url | text NOT NULL UNIQUE | git repo URL |
 | defaultBranch | text NOT NULL | default 'main' |
+| lastFetchedAt | integer/timestamp | nullable, updated by ProjectSyncManager |
 | createdAt, updatedAt | integer/timestamp | |
 
 ### initiative_projects (junction)