feat(FN-1196): support API-key providers in dashboard auth flow

- Wrap dashboard auth storage with API-key provider helpers derived from model registry providers
- Normalize provider display names and bridge set/clear/has API-key operations to AuthStorage credentials
- Expand route and onboarding tests for mixed OAuth/API-key states and API-key-authenticated setup paths
- Stabilize assignment-trigger heartbeat timing test by replacing fixed delays with waitFor assertions

packages/engine/src/agent-heartbeat.test.ts

@@ -2438,10 +2438,11 @@ describe("HeartbeatTriggerScheduler", () => {
 
       eventStore.emit("agent:assigned", agent, "FN-001");
 
-      // Wait for async event handler
-      await new Promise((resolve) => setTimeout(resolve, 10));
+      // Allow asynchronous assignment listeners to run in heavily loaded test environments.
+      await vi.waitFor(() => {
+        expect(callback).toHaveBeenCalledOnce();
+      }, { timeout: 1000 });
 
-      expect(callback).toHaveBeenCalledOnce();
       expect(callback).toHaveBeenCalledWith("agent-test", "assignment", {
         taskId: "FN-001",
         wakeReason: "assignment",