refactor: remove token-refresh, use env-based auth only

Delete token-refresh.ts and credentials.json sync. Auth is now
via CLAUDE_CODE_OAUTH_TOKEN in .env (1-year setup-token).
No more auto-refresh loop or credentials.json dependency.

src/index.ts

@@ -57,10 +57,6 @@ import {
   isSessionCommandAllowed,
 } from './session-commands.js';
 import { startSchedulerLoop } from './task-scheduler.js';
-import {
-  startTokenRefreshLoop,
-  stopTokenRefreshLoop,
-} from './token-refresh.js';
 import { Channel, ChannelMeta, NewMessage, RegisteredGroup } from './types.js';
 import { logger } from './logger.js';
 
@@ -1017,7 +1013,6 @@ async function main(): Promise<void> {
   // Graceful shutdown handlers
   const shutdown = async (signal: string) => {
     logger.info({ signal }, 'Shutdown signal received');
-    stopTokenRefreshLoop();
     await queue.shutdown(10000);
     for (const ch of channels) await ch.disconnect();
     process.exit(0);
@@ -1077,9 +1072,6 @@ async function main(): Promise<void> {
     process.exit(1);
   }
 
-  // Start OAuth token auto-refresh (before subsystems that spawn agents)
-  startTokenRefreshLoop();
-
   // Start subsystems (independently of connection handler)
   startSchedulerLoop({
     registeredGroups: () => registeredGroups,