collab: Include max monthly spend preference in LLM token (#18955)

This PR updates the LLM token claims to include the maximum monthly
spend.

Release Notes:

- N/A

crates/collab/src/rpc.rs

@@ -4917,10 +4917,14 @@ async fn get_llm_api_token(
     if Utc::now().naive_utc() - account_created_at < MIN_ACCOUNT_AGE_FOR_LLM_USE {
         Err(anyhow!("account too young"))?
     }
+
+    let billing_preferences = db.get_billing_preferences(user.id).await?;
+
     let token = LlmTokenClaims::create(
         user.id,
         user.github_login.clone(),
         session.is_staff(),
+        billing_preferences,
         has_llm_closed_beta_feature_flag,
         session.has_llm_subscription(&db).await?,
         session.current_plan(&db).await?,