fix: propagate dispatcher origin to composed interceptors

[jibin7jose]

Summary
This change ensures that composed interceptors receive the dispatcher origin automatically when a Client or Pool dispatches a request without an explicit origin in the request options.

What changed
Propagate the dispatcher’s base origin into request options before interceptor dispatch.
Preserve existing behavior for requests that already specify an origin.
Update interceptor regression tests to cover Client and Pool requests without an explicit origin.
Why
Some interceptors depend on opts.origin being present. Without this propagation, requests dispatched through a composed Client or Pool could bypass interceptor behavior unexpectedly.

Testing
Verified the interceptor test suite with:
npm run test:interceptors
Co-authored-by: [jibinjose884@gmail.com]

[mcollina]

lgtm

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.53%. Comparing base (f6bfa14) to head (9272d07).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5624      +/-   ##
==========================================
+ Coverage   93.50%   93.53%   +0.02%     
==========================================
  Files         110      110              
  Lines       38451    38460       +9     
==========================================
+ Hits        35955    35974      +19     
+ Misses       2496     2486      -10     

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