chore: ignore local frontend symlink

~/services/delega/frontend is a per-developer dev-loop convenience
pointing at an external workspace path. It has been appearing as
untracked on every git status and was nearly committed by accident
this session (reverted locally before push). Adding it to .gitignore
stops the nag and forecloses that class of near-miss.

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

Author: marty-clawed-bot

.gitignore

@@ -49,5 +49,8 @@ data/
 # Node (if applicable)
 node_modules/
 
+# Local frontend symlink (user's dev convenience; not part of the repo)
+frontend
+
 # Internal release check (contains infrastructure details)
 scripts/release-check.sh