Fix export and detail API inconsistencies for remote auth config

[amirejaz]

Problem

The export and detail APIs had several inconsistencies that were blocking UI development:

1. Missing use_pkce attribute in export endpoint responses
2. PascalCase field names in remote_auth_config violating JSON schema
3. Inconsistent auth config between export and detail endpoints

Solution

• Added UsePKCE field to RemoteAuthConfig struct with proper JSON tags
• Fixed field name casing to use snake_case (use_pkce, client_id, etc.)
• Updated all conversion functions to include UsePKCE field
• Ensured both endpoints return identical auth configuration structure

Testing

• All existing tests pass
• Verified JSON serialization includes use_pkce field for both true values
• Confirmed consistent field naming between export and detail endpoints

Impact

• UI can now reliably access use_pkce field for workload duplication
• Both export and detail endpoints return consistent JSON structure
• API responses now match the documented JSON schema

fixes #2188

[codecov]

Codecov Report

❌ Patch coverage is 33.33333% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 53.12%. Comparing base (df489b6) to head (76213a9).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
pkg/api/v1/workload_service.go	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2198      +/-   ##
==========================================
+ Coverage   53.06%   53.12%   +0.05%     
==========================================
  Files         222      222              
  Lines       28913    28916       +3     
==========================================
+ Hits        15344    15361      +17     
+ Misses      12429    12410      -19     
- Partials     1140     1145       +5     

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