chore: converge CountryService protected branches

[natthapolvanasrivilai]

Outcome

Converges develop onto the exact reviewed CountryService tree already promoted to main by #38, while retaining both branch histories.

Integrity

• Result tree SHA: 421c1bef6dbcc7468512e45f9f56a9352ed0830e
• Result tree is byte-identical to current main (16d99ec97014363c2d4121fd6ec99c671cdf1e8c).
• Preserves the complete 219-commit Clean Architecture feature history from develop and the three newer main maintenance commits.
• Replaces old branch deployment workflows with the reviewed validation-only workflow set; no image publication or GitOps/environment mutation.

Validation

• dotnet restore Maliev.CountryService.slnx --locked-mode: passed.
• Release build: 0 warnings, 0 errors.
• Full tests: 263/263 passed.
• dotnet format --verify-no-changes: passed.
• Transitive NuGet vulnerability audit: no vulnerable packages.
• Actionlint: passed.
• Gitleaks current-tree scan: no leaks.
• Historical-only documentation examples remain in inherited history but are absent from the current tree; no history rewrite is performed.
• Existing exact-main validation run 29648370578: green.

Safety boundary

No deployment, GCP/GKE/IAM/secrets change, image publication, GitOps write, or database operation.