🐛 fix: Multiple deepseek-reasoner errors

[sxjeru]

💻 变更类型 | Change Type

• ✨ feat
• 🐛 fix
• ♻️ refactor
• 💄 style
• 👷 build
• ⚡️ perf
• 📝 docs
• 🔨 chore

🔀 变更说明 | Description of Change

修复 deepseek-r1 的下述报错。当前采用直接剔除不合规消息的方案，应当有更合适的方案，比如通过添加一条空消息使其合规。

The first message (except the system message) of deepseek-reasoner must be a user message, 
but an assistant message detected.

deepseek-reasoner does not support successive user or assistant messages (messages[x] and messages[x] in your input). 
You should interleave the user/assistant messages in the message sequence.

📝 补充信息 | Additional Information

[vercel]

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[codecov]

Codecov Report

Attention: Patch coverage is 77.27273% with 5 lines in your changes missing coverage. Please review.

Project coverage is 92.15%. Comparing base (979849c) to head (7c80d96).
Report is 38 commits behind head on main.

Files with missing lines	Patch %	Lines
src/libs/agent-runtime/deepseek/index.ts	77.27%	5 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5548      +/-   ##
==========================================
- Coverage   92.15%   92.15%   -0.01%     
==========================================
  Files         640      640              
  Lines       56821    56840      +19     
  Branches     4238     2886    -1352     
==========================================
+ Hits        52365    52379      +14     
- Misses       4456     4461       +5     

Flag	Coverage Δ
app	92.15% <77.27%> (-0.01%)	⬇️
server	97.99% <ø> (ø)

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