story-kit: add 5_done to commit-worthy stages

Keep done stage committed so accepted work is in git history.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

server/src/io/watcher.rs

@@ -159,7 +159,7 @@ fn git_add_work_and_commit(git_root: &Path, message: &str) -> Result<bool, Strin
 /// Intermediate stages (current, qa, merge, done) are transient pipeline state
 /// that don't need to be committed — they're only relevant while the server is
 /// running and are broadcast to WebSocket clients for real-time UI updates.
-const COMMIT_WORTHY_STAGES: &[&str] = &["1_upcoming", "6_archived"];
+const COMMIT_WORTHY_STAGES: &[&str] = &["1_upcoming", "5_done", "6_archived"];
 
 /// Return `true` if changes in `stage` should be committed to git.
 fn should_commit_stage(stage: &str) -> bool {