Fix rewrite of unqualified reference

[jonesbusy]

Description

Fix rewrite of unqualified reference

AI assisted PR with human review

Testing done

mvn clean install and added tests

Submitter checklist

• I have read and understood the CONTRIBUTING guide
• I have run mvn license:update-file-header, mvn spotless:apply, pre-commit run -a, mvn clean install before opening the PR

[codecov]

Codecov Report

❌ Patch coverage is 81.25000% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 87.58%. Comparing base (88b096f) to head (0d21b43).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/main/java/land/oras/auth/RegistriesConf.java	81.25%	1 Missing and 2 partials ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main     #692      +/-   ##
============================================
+ Coverage     86.75%   87.58%   +0.83%     
- Complexity      960      963       +3     
============================================
  Files            43       43              
  Lines          2974     2988      +14     
  Branches        371      374       +3     
============================================
+ Hits           2580     2617      +37     
+ Misses          238      211      -27     
- Partials        156      160       +4     

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