refactor: chat service & support sendReplyMessage api

[Ricbet]

Types

• 🎉 New Features
• 🪚 Refactors

Background or solution

• 重构 ChatService ，区分出 chat internal service 和 chat api service
• 新增 sendReplyMessage 方法，能主动以 ai role 的身份发送 reply 消息

Changelog

[railway-app]

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[codecov]

Codecov Report

Attention: Patch coverage is 12.00000% with 22 lines in your changes are missing coverage. Please review.

Project coverage is 56.50%. Comparing base (83d9d25) to head (35839ea).

Files	Patch %	Lines
...ges/ai-native/src/browser/chat/chat.api.service.ts	0.00%	14 Missing ⚠️
...s/ai-native/src/browser/chat/chat-agent.service.ts	0.00%	3 Missing ⚠️
packages/ai-native/src/browser/index.ts	0.00%	3 Missing ⚠️
...i-native/src/browser/chat/chat.internal.service.ts	0.00%	1 Missing ⚠️
packages/ai-native/src/node/index.ts	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3539      +/-   ##
==========================================
- Coverage   56.51%   56.50%   -0.02%     
==========================================
  Files        1482     1483       +1     
  Lines       90364    90376      +12     
  Branches    18582    17551    -1031     
==========================================
- Hits        51069    51066       -3     
- Misses      35762    39287    +3525     
+ Partials     3533       23    -3510     

Flag	Coverage Δ
jsdom	51.82% <12.00%> (-0.02%)	⬇️
node	15.76% <8.00%> (+<0.01%)	⬆️

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