fix: support base_url for embedding model

[Juliaj]

Purpose

• May a use models from OpenRouter? #755

Proposed Changes

What does this PR add, remove or fix?

Issues

• Links to relevant issues

Testing

• How was it tested, what were the results?

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 65.79%. Comparing base (44ce82e) to head (509f311).
⚠️ Report is 1 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #756      +/-   ##
==========================================
+ Coverage   65.44%   65.79%   +0.35%     
==========================================
  Files          78       78              
  Lines        3403     3403              
==========================================
+ Hits         2227     2239      +12     
+ Misses       1176     1164      -12     

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