v1.39.0

What's Changed

• ci: drop unmonitored nightly schedules from integration & examples workflows by @smolpaws in #4291
• fix(llm): generalize model capability resolution by @neubig in #4200
• test(settings): reject unversioned persisted shape changes by @neubig in #4295
• feat(agent-server): add MCP settings CRUD endpoints by @neubig in #4294
• test(sdk): stabilize MCP stdio integration tests by @simonrosenberg in #4301
• Release v1.39.0 by @all-hands-bot in #4300

Full Changelog: v1.38.0...v1.39.0