Fix SSE events to include missing gitDeletedCount field

The git-watcher was sending incomplete git status updates via SSE,
missing the gitDeletedCount field. This caused the UI to lose the
deleted files count after receiving real-time updates.

Note: gitAddedCount is defined in the Session type but is not computed
by the git status utility and remains unused throughout the codebase.

web/src/server/services/git-watcher.ts

@@ -270,6 +270,7 @@ export class GitWatcher {
         gitModifiedCount: status.modified,
         gitUntrackedCount: status.untracked,
         gitStagedCount: status.staged,
+        gitDeletedCount: status.deleted,
         gitAheadCount: status.ahead,
         gitBehindCount: status.behind,
       };