chore: stop tracking .claude/scheduled_tasks.lock

It's a machine-local runtime lock file that shouldn't be in the repo;
remove it and add it to .gitignore.

Author: XXPermanentXX

.claude/scheduled_tasks.lock

@@ -33,6 +33,7 @@ tools/generated
 .claude/worktrees/
 .claude/settings.json
 .claude/settings.local.json
+.claude/scheduled_tasks.lock
 .cursor/
 .qwen/
 .playwright-mcp/