refactor: unify skill sync, remove commands directory

- Remove commands/ sync from agent-runner (skills/ is SSOT for both agents)
- Remove ~/.codex/skills/ as source (use ~/.claude/skills/ only)
- Codex uses $skill prefix, Claude Code uses /skill — both read from skills/
- Minor formatting fixes in config.ts, group-queue.test.ts, index.ts

src/index.ts

@@ -235,10 +235,7 @@ async function processGroupMessages(chatJid: string): Promise<boolean> {
   const resetIdleTimer = () => {
     if (idleTimer) clearTimeout(idleTimer);
     idleTimer = setTimeout(() => {
-      logger.debug(
-        { group: group.name },
-        'Idle timeout, closing agent stdin',
-      );
+      logger.debug({ group: group.name }, 'Idle timeout, closing agent stdin');
       queue.closeStdin(chatJid);
     }, IDLE_TIMEOUT);
   };