fix(core): pass domain name for proxy fetcher

[NaveenChand755]

Summary: Pass Auth0 domain to proxy-mode API clients instead of an empty string.

What: Changed domain: '' to domain: config.domain ?? '' in both createMyAccountClient and createMyOrganizationClient for proxy mode.

Why: In proxy mode, routing uses baseUrl, not domain. However, the domain is still needed to construct the audience auth parameter in the fetcher. Previously it was hardcoded to an empty string, making it unavailable. This aligns proxy mode with normal mode where the domain is already passed through.

Packages

• packages/core
• packages/react
• examples

References

Testing

How can this be verified? Note anything intentionally not covered by tests and why.

• This change adds unit test coverage
• Tested for both SPA and RWA flows, all example apps working
• All existing and new tests complete without errors

Checklist

• Breaking change
• Requires docs update
• Backward compatible

Contributing

• I have read the Auth0 general contribution guidelines
• I have read the Auth0 Code of Conduct

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.42%. Comparing base (c1fa8fd) to head (2ae2579).

Additional details and impacted files

@@           Coverage Diff            @@
##             main     #266    +/-   ##
========================================
  Coverage   89.42%   89.42%            
========================================
  Files         159      159            
  Lines       13325    13325            
  Branches     1357     1749   +392     
========================================
  Hits        11916    11916            
  Misses       1409     1409            

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