fix: address code quality issues in session pool, approval, and main

- session.ts: add onReconnect callback so reconnected socket replaces stale pool entry
- session-pool.ts: pass onReconnect to update pool on reconnect; add closeAll() to gracefully end WebSocket connections on shutdown
- approval.ts: use approved flag so double-approval race (updateMany count=0) returns null instead of sending duplicate forward jobs
- main.ts: wrap pool.add() in try/catch to continue if one account fails; replace silent groupMap fallback with explicit error log and early return; call pool.closeAll() before BullMQ shutdown to prevent hanging sockets
- Tests: add closeAll() test to session-pool.test.ts; add double-approval race test to approval.test.ts (56 tests total, all passing)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/worker/src/whatsapp/session-pool.ts

@@ -28,6 +28,10 @@ export class WhatsAppSessionPool {
       (msg) => onMessage(msg, accountId),
       (reaction) => onReaction(reaction, accountId),
       (groups) => onGroups(groups, accountId),
+      (newSocket) => {
+        logger.info({ accountId }, 'Session reconnected — updating pool');
+        this.sessions.set(accountId, newSocket);
+      },
     );
     this.sessions.set(accountId, sock);
   }
@@ -57,4 +61,17 @@ export class WhatsAppSessionPool {
       logger.info({ accountId }, 'Session removed');
     }
   }
+
+  async closeAll(): Promise<void> {
+    logger.info({ count: this.sessions.size }, 'Closing all WhatsApp sessions');
+    for (const [accountId, sock] of this.sessions) {
+      try {
+        sock.end(undefined);
+        logger.info({ accountId }, 'Session closed');
+      } catch (err) {
+        logger.error({ accountId, err }, 'Error closing session');
+      }
+    }
+    this.sessions.clear();
+  }
 }