Review MCP session Durable Object 30s keepalive alarm (hibernation/cost)

[amondnet]

Sub-task of #3 (Fix E).

The MCP session DO fires a ~30s keepalive alarm at ~0 CPU / 30s wall, keeping the DO from hibernating: apps/host-cloudflare/src/mcp/session-durable-object.ts. Unrelated to page latency.

Tasks:

• Confirm whether the 30s self-rescheduling alarm is necessary.
• Allow the DO to hibernate when idle; review cost impact.

---

• To see the specific tasks where the Asana app for GitHub is being used, see below:
  • https://app.asana.com/0/0/1216031173813976