feat(FN-1259): add review handoff feature for user task assignment

- Add assigneeUserId field to Task and TaskDetail types
- Add reviewHandoffPolicy project setting (manual/auto/delegated modes)
- Implement handoff detection policy in executor with session state tracking
- Add dashboard API routes for user assignment and handoff endpoints
- Add frontend API functions for review handoff UI integration
- Add tests for review handoff feature endpoints
- Fix test duplicates and finalize documentation

packages/dashboard/src/routes.test.ts

@@ -1825,7 +1825,6 @@ describe("PATCH /tasks/:id", () => {
       planningModelId: null,
       thinkingLevel: undefined,
       assigneeUserId: null,
-      assigneeUserId: null,
     });
     expect(res.body.dependencies).toEqual(["FN-002"]);
   });
@@ -1852,7 +1851,6 @@ describe("PATCH /tasks/:id", () => {
       planningModelId: null,
       thinkingLevel: undefined,
       assigneeUserId: null,
-      assigneeUserId: null,
     });
   });
 
@@ -1889,7 +1887,6 @@ describe("PATCH /tasks/:id", () => {
       planningModelId: null,
       thinkingLevel: undefined,
       assigneeUserId: null,
-      assigneeUserId: null,
     });
   });