feat(dashboard-agent): stay warm for 5 minutes and wait 7 days between turns

```ts
export const dashboardAgent = chat.agent({
  idleTimeoutInSeconds: 300,
  turnTimeout: "7d",
  maxDuration: 86_400,
  // ...
});
```

The dashboard agent now stays warm for 5 minutes after each answer and,
once suspended, waits up to 7 days for the next message. Quick
follow-ups answer from the same live run, returning to a chat days later
resumes it rather than starting a new run, and the chat run's compute
limit is raised to a day so long conversations aren't cut off.

Mono-RevId: 7b7ac10420f36e9cc76b371b40faa9b7245e1b48

Author: ericallam

internal-packages/dashboard-agent/src/dashboard-agent.ts

@@ -385,8 +385,9 @@ export const dashboardAgent = chat.agent({
   storage: dashboardAgentStorage,
   // A watch action files a request and answers it with a turn; see `watch-actions.ts`.
   actionSchema: dashboardAgentActionSchema,
-  // Short idle window so suspended runs release their DB pool.
-  idleTimeoutInSeconds: 60,
+  idleTimeoutInSeconds: 300,
+  turnTimeout: "7d",
+  maxDuration: 86_400,
 
   uiMessageStreamOptions: {
     // The stream carries the same sentence the transcript keeps, so the live chunk