Add error boundary to the local API server

[l2ysho]

src/lib/local-api-server.ts:86-103 reads the request body and awaits the route handler with no try/catch. A client aborting mid-body, or a handler that throws, becomes an unhandled rejection and can kill the CLI process during apify login or apify actor edit-input-schema.

Also, JSON.parse accepts null and arrays, so handlers reading properties off body get a non-object.

• Wrap body read + dispatch in try/catch → 500 on handler throw
• Reject non-object JSON with 400
• Skip writing if res.destroyed || res.writableEnded

From the review of #1304. Part of #1305.

---

Generated by Claude Code