feat(FN-1085): align agent routing and runtime contracts

- Harden core AgentStore lifecycle behavior and heartbeat runtime integration paths
- Align dashboard agent APIs, server routes, and agent UI flows with the updated contract
- Tighten CLI agent/message command routing and validate payload handling semantics
- Expand test coverage across core, dashboard, engine, and CLI for route, heartbeat, and instruction regressions

packages/dashboard/app/hooks/useAgents.ts

@@ -35,8 +35,7 @@ export function useAgents(projectId?: string) {
 
   // SSE subscription for agent events
   useEffect(() => {
-    if (!projectId) return;
-    const query = `?projectId=${encodeURIComponent(projectId)}`;
+    const query = projectId ? `?projectId=${encodeURIComponent(projectId)}` : "";
     const es = new EventSource(`/api/events${query}`);
 
     const refresh = () => {