perf(todo-continuation): add cooldown and stagnation cap to prevent re-injection loops

src/hooks/todo-continuation-enforcer/session-state.ts

@@ -38,6 +38,7 @@ export function createSessionStateStore(): SessionStateStore {
       state.countdownInterval = undefined
     }
 
+    state.inFlight = false
     state.countdownStartedAt = undefined
   }