fix: correct worktree-start heredoc bash syntax (#438)

Move the command-substitution closing paren after the heredoc terminator
so bash -n passes and worktree lock checks run correctly.

Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>

scripts/worktree-start

@@ -42,7 +42,7 @@ repo_root="$(cd "$script_dir/.." && pwd)"
 
 # Enforce issue-linked, traceable branch names (issue → branch → worktree → PR).
 if [[ "$allow_unlinked" -eq 0 ]]; then
-  locked_branch=$(PYTHONPATH="$repo_root" python3 - <<'PY' "$branch")
+  locked_branch=$(PYTHONPATH="$repo_root" python3 - "$branch" <<'PY'
 import sys
 import issue_lock_store
 
@@ -53,7 +53,7 @@ if not lock:
     sys.exit(1)
 print(lock.get("branch_name", ""), end="")
 PY
-  )
+)
   if [[ -z "$locked_branch" ]]; then
     echo "Error: No issue lock found for branch '$branch'. Lock the issue before branch creation (fail closed)." >&2
     exit 2