chore(openapi): regenerate Agent SDK spec from SDK 1.52.0

The OpenAPI sync workflow has been a no-op since 2026-02-15, leaving the
published spec at 40 paths / 106 endpoints while the SDK exposes 135
paths / 245 endpoints. Regenerated with the SDK's canonical exporter.

Co-authored-by: openhands <openhands@all-hands.dev>

Author: openhands-agent