fix(M2-005,M2-006): enforce user ownership at repo level for conversations and agents (#293)

Co-authored-by: Jason Woltje <jason@diversecanvas.com>
Co-committed-by: Jason Woltje <jason@diversecanvas.com>

apps/gateway/src/__tests__/resource-ownership.test.ts

@@ -57,11 +57,13 @@ function createBrain() {
 describe('Resource ownership checks', () => {
   it('forbids access to another user conversation', async () => {
     const brain = createBrain();
-    brain.conversations.findById.mockResolvedValue({ id: 'conv-1', userId: 'user-2' });
+    // The repo enforces ownership via the WHERE clause; it returns undefined when the
+    // conversation does not belong to the requesting user.
+    brain.conversations.findById.mockResolvedValue(undefined);
     const controller = new ConversationsController(brain as never);
 
     await expect(controller.findOne('conv-1', { id: 'user-1' })).rejects.toBeInstanceOf(
-      ForbiddenException,
+      NotFoundException,
     );
   });