feat(provider): add railway support

[o-az]

🔗 Linked issue

❓ Type of change

• 📖 Documentation (updates to the documentation, readme, or JSdoc annotations)
• 🐞 Bug fix (a non-breaking change that fixes an issue)
• 👌 Enhancement (improving an existing functionality like performance)
• ✨ New feature (a non-breaking change that adds functionality)
• 🧹 Chore (updates to the build process or auxiliary tools and libraries)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

Adding support for https://railway.app. Not entirely sure I'm doing this right. Please let me know if that's not how it should be.

Ref: https://docs.railway.app/reference/variables#railway-provided-variables

📝 Checklist

• I have linked an issue or discussion.
• I have updated the documentation accordingly.

[pi0]

Thanks!

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (bfaedd7) 80.46% compared to head (e7af614) 80.63%.
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #106      +/-   ##
==========================================
+ Coverage   80.46%   80.63%   +0.16%     
==========================================
  Files          10       10              
  Lines         343      346       +3     
  Branches       32       32              
==========================================
+ Hits          276      279       +3     
  Misses         61       61              
  Partials        6        6              

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