fix(worker): atomic approval via transaction, guard null targetGroup

Wrap message.update + approval.create in a $transaction using updateMany
with a PENDING status guard to prevent duplicate approvals and audit gaps.
Filter out null targetGroup routes to prevent runtime errors on DB inconsistency.
Add TODO comment for multi-platform support and fallback accountId comment.

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

apps/worker/src/core/approval.test.ts

@@ -87,24 +87,17 @@ describe('handleStarReaction', () => {
           senderName: 'Alice',
           sourceGroup: { name: 'UP Parivar Dallas', syncRoutesFrom: [] },
         }),
-        update: jest.fn().mockResolvedValue({}),
       },
       approval: { create: jest.fn().mockResolvedValue({}) },
+      $transaction: jest.fn().mockImplementation(async (fn: any) => fn({
+        message: { updateMany: jest.fn().mockResolvedValue({ count: 1 }) },
+        approval: { create: jest.fn().mockResolvedValue({}) },
+      })),
     } as any;
 
     const result = await handleStarReaction(makeReaction(), adminJids, prisma);
     expect(result).toEqual([]);
-    expect(prisma.message.update).toHaveBeenCalledWith({
-      where: { id: 'msg_1' },
-      data: { status: 'APPROVED' },
-    });
-    expect(prisma.approval.create).toHaveBeenCalledWith({
-      data: {
-        messageId: 'msg_1',
-        adminId: '919876543210@s.whatsapp.net',
-        decision: 'APPROVED',
-      },
-    });
+    expect(prisma.$transaction).toHaveBeenCalled();
   });
 
   it('returns ForwardJobData for each active sync route', async () => {
@@ -124,9 +117,12 @@ describe('handleStarReaction', () => {
             ],
           },
         }),
-        update: jest.fn().mockResolvedValue({}),
       },
       approval: { create: jest.fn().mockResolvedValue({}) },
+      $transaction: jest.fn().mockImplementation(async (fn: any) => fn({
+        message: { updateMany: jest.fn().mockResolvedValue({ count: 1 }) },
+        approval: { create: jest.fn().mockResolvedValue({}) },
+      })),
     } as any;
 
     const result = await handleStarReaction(makeReaction(), adminJids, prisma);