refactor: remove config dependency from RepoCheckVersionService

[StevenTCramer]

Summary

• Removed config-related files from Amuru (public repo no longer references private "ganda" branding)
• Refactored IRepoCheckVersionService to expose two focused methods instead of one strategy-switching method
• Removed IRepoConfigService dependency from RepoCheckVersionService

Changes

Deleted files:

• IRepoConfigService.cs
• RepoConfigService.cs
• RepoConfig.cs
• RepoConfigJsonContext.cs

API changes:

Before:

Task<CheckVersionResult> CheckAsync(string? strategy, string? package, string? tag, ...);

After:

Task<GitTagCheckResult> CheckGitTagVersionAsync(string? tag = null, CancellationToken = default);
Task<NuGetCheckResult> CheckNuGetVersionAsync(IReadOnlyList<string> packages, CancellationToken = default);

Test results

All 8 tests pass.

Follow-up

This is step 1 of a larger migration:

1. ✅ Refactor Amuru (this PR)
2. Release new Amuru version
3. Nuru.DevCli updates to use new Amuru
4. Amuru's dev-cli updates to use Nuru.DevCli shared endpoints

Note: The dev-cli check-version command in this repo still uses the old API and will be updated in step 4.