fix(extension): stateless SW, pull tab state instead of ports

[gaomeng1900]

What

Refactor TabsController to pull tab state on demand instead of maintaining long-lived ports in the MV3 service worker. Removes setupTabEventsPort and all port-based tab event pushing so the background worker stays fully stateless and survives idle kills / stalled updates without leaving the side panel unresponsive.

Closes

• [Bug] Extension becomes unresponsive (service worker inactive) #452

Supersedes

• fix(extension): show startup failure guidance #496
• fix(extension): detect stalled background worker #498.

Type

• Breaking change
• Bug fix
• Feature / Improvement
• Refactor / Chores
• Documentation / Website / Demo / Testing

Testing

• Tested in modern browsers
• No console errors
• Types/doc added

Requirements / 要求

• I have read and follow the Code of Conduct and Contributing Guide . / 我已阅读并遵守行为准则。
• This PR is NOT generated by a bot or AI agent acting autonomously. I have authored or meaningfully reviewed every change. / 此 PR 不是由 bot 或 AI 自主生成的，我已亲自编写或充分审查了每一处变更。