fix(repo): remove stray .claude/worktrees gitlink and ignore worktree dirs

A Claude Code worktree directory (.claude/worktrees/peaceful-northcutt) was
accidentally committed as a gitlink in dde4f56. With no matching .gitmodules
entry, every submodule-aware git operation errors on it — visibly as the
'fatal: No url found for submodule path' exit-128 warning in CI checkout
cleanup on all recent runs.

Remove the gitlink from the index and gitignore .claude/worktrees/ so a
local worktree can never be committed again.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: QSchlegel

.claude/worktrees/peaceful-northcutt

@@ -57,3 +57,6 @@ scripts/bot-ref/bot-wallet.json
 # CI artifacts
 ci-artifacts/
 .ci-dist/
+
+# Claude Code worktrees and local session state (never commit)
+.claude/worktrees/