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.test.ts

@@ -5,6 +5,7 @@ jest.mock('./session', () => ({
   createWhatsAppSession: jest.fn().mockResolvedValue({
     sendMessage: jest.fn().mockResolvedValue({}),
     logout: jest.fn().mockResolvedValue({}),
+    end: jest.fn(),
   }),
 }));
 
@@ -55,6 +56,21 @@ describe('WhatsAppSessionPool', () => {
     await expect(pool.remove('acc_unknown')).resolves.not.toThrow();
   });
 
+  it('closeAll() calls end() on all sessions and clears the pool', async () => {
+    await pool.add('acc_1', './sessions/1', jest.fn(), jest.fn(), jest.fn());
+    await pool.add('acc_2', './sessions/2', jest.fn(), jest.fn(), jest.fn());
+    expect(pool.getAll().size).toBe(2);
+
+    const sock1 = pool.get('acc_1')!;
+    const sock2 = pool.get('acc_2')!;
+
+    await pool.closeAll();
+
+    expect(sock1.end).toHaveBeenCalledWith(undefined);
+    expect(sock2.end).toHaveBeenCalledWith(undefined);
+    expect(pool.getAll().size).toBe(0);
+  });
+
   it('add() injects accountId into onMessage callback', async () => {
     const onMessage = jest.fn();
     const { createWhatsAppSession } = require('./session');