Fix chat copy icons and add Kimi support

[Idema2455]

Summary

• Restore ChatGPT sidebar conversation icon discovery and robust conversation ID parsing.
• Keep sidebar copy icons visible and reinject them correctly after SPA navigation and sidebar updates.
• Support DeepSeek history responses with both top-level content and fragments, excluding private THINK fragments.
• Add Kimi support for kimi.ai and kimi.com, including authenticated message retrieval, conversation ordering, text-block extraction, plugin registration, host permissions, and documentation.
• Improve copy failure messages so structured and unexpected errors are surfaced.

Validation

• pnpm --filter @ctxport/core-plugins test -- --run src/plugins/kimi/plugin.test.ts — passed (4 tests across Kimi and DeepSeek suites).
• pnpm --filter @ctxport/core-plugins typecheck — passed.
• pnpm --filter @ctxport/extension typecheck — passed.
• pnpm --filter @ctxport/extension build — passed.
• Push pre-hook: repository lint and typecheck tasks passed after fixing two new lint errors; existing CRLF Prettier warnings remain.
• git diff --check — passed.