feat: Adds guideline extraction & validation routes

[frgfm]

This PR introduces the following modifications:

• adds several routes to parse guidelines from text, from github repo and to generate examples from a guideline
• updates LLM client and github client accordingly

[codecov]

Codecov Report

Attention: 24 lines in your changes are missing coverage. Please review.

Comparison is base (0499b63) 85.08% compared to head (b3d4342) 83.78%.

Files	Patch %	Lines
src/app/services/openai.py	52.38%	10 Missing ⚠️
src/app/api/api_v1/endpoints/repos.py	50.00%	7 Missing ⚠️
src/app/api/api_v1/endpoints/guidelines.py	60.00%	4 Missing ⚠️
src/app/api/api_v1/endpoints/compute.py	0.00%	2 Missing ⚠️
src/app/services/github.py	96.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #35      +/-   ##
==========================================
- Coverage   85.08%   83.78%   -1.30%     
==========================================
  Files          28       28              
  Lines         818      882      +64     
==========================================
+ Hits          696      739      +43     
- Misses        122      143      +21     

Flag	Coverage Δ
unittests	83.78% <70.73%> (-1.30%)	⬇️

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