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

apps/server/db/schema.ts

@@ -453,6 +453,7 @@ export const projects = sqliteTable('projects', {
   name: text('name').notNull().unique(),
   url: text('url').notNull().unique(),
   defaultBranch: text('default_branch').notNull().default('main'),
+  lastFetchedAt: integer('last_fetched_at', { mode: 'timestamp' }),
   createdAt: integer('created_at', { mode: 'timestamp' }).notNull(),
   updatedAt: integer('updated_at', { mode: 'timestamp' }).notNull(),
 });