feat(FN-940): allow terminated agents to restart as active or running

- Remove blanket block on terminated→any state transitions in agent-store
- Add active and running as valid transitions from terminated state in types
- Update tests to verify terminated→active and terminated→running succeed
- Add tests for invalid terminated transitions (idle, paused) still throwing

packages/core/src/agent-store.ts

@@ -244,10 +244,6 @@ export class AgentStore extends EventEmitter {
         return agent; // No change needed
       }
 
-      if (currentState === "terminated") {
-        throw new Error(`Cannot transition from terminated state to ${newState}`);
-      }
-
       const validTransitions = AGENT_VALID_TRANSITIONS[currentState];
       if (!validTransitions.includes(newState)) {
         throw new Error(