Fix swagger generation for ImageMetadata embedded fields

[lujunsan]

Remove yaml:",inline" tag from BaseServerMetadata embedding in
ImageMetadata struct. The yaml-only tag caused swaggo v2.0.0-rc5
to skip inlining the embedded fields in the OpenAPI schema, resulting
in missing fields like name, description, tier, status, etc.

Anonymous struct embedding without tags allows both proper JSON
marshaling and correct swagger schema generation.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 64.18%. Comparing base (1a1251b) to head (a9934c8).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3311      +/-   ##
==========================================
- Coverage   64.20%   64.18%   -0.02%     
==========================================
  Files         365      365              
  Lines       35249    35249              
==========================================
- Hits        22630    22626       -4     
- Misses      10805    10812       +7     
+ Partials     1814     1811       -3     

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