v1.12.0

## What's Changed

**Stateless extension tab sync** - TabsController pulls tab state on demand instead of long-lived ports, so the MV3 service worker stays stateless and survives idle kills without stalling the side panel.

**Tab status in agent context** - Tab summaries now include each tab's loading status for the LLM.

* docs: improve README copy and quick start by @gaomeng1900 in https://github.com/alibaba/page-agent/pull/592
* fix(ci): format README and align markdown tooling with Prettier by @gaomeng1900 in https://github.com/alibaba/page-agent/pull/593
* chore(deps-dev): bump the development-dependencies group with 8 updates by @dependabot[bot] in https://github.com/alibaba/page-agent/pull/595
* fix(extension): stateless SW, pull tab state instead of ports by @gaomeng1900 in https://github.com/alibaba/page-agent/pull/596
* feat(extension): add tab status to context by @gaomeng1900 in https://github.com/alibaba/page-agent/pull/599
* chore: add self-hosted runners by @gaomeng1900 in https://github.com/alibaba/page-agent/pull/602
* docs: point CI badge at main-ci.yml by @gaomeng1900 in https://github.com/alibaba/page-agent/pull/603
* chore(llms): limit live test concurrency by @gaomeng1900 in https://github.com/alibaba/page-agent/pull/604


**Full Changelog**: https://github.com/alibaba/page-agent/compare/v1.11.0...v1.12.0