feat: Support extracting reasoning content from regular content

[CH3CHO]

Ⅰ. Describe what this PR did

Support extracting reasoning content from regular content.

Tested with deepseek-r1:1.5b hosted in Ollama.

Original non-stream response:

Extracted non-stream response:

Extracted stream response:

Ⅱ. Does this pull request fix one issue?

Ⅲ. Why don't you add test cases (unit test/integration test)?

Ⅳ. Describe how to verify it

Ⅴ. Special notes for reviews

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 43.30%. Comparing base (ef31e09) to head (30ed2f1).
Report is 359 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1929      +/-   ##
==========================================
+ Coverage   35.91%   43.30%   +7.39%     
==========================================
  Files          69       78       +9     
  Lines       11576    12479     +903     
==========================================
+ Hits         4157     5404    +1247     
+ Misses       7104     6737     -367     
- Partials      315      338      +23     

see 73 files with indirect coverage changes

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