Enforce dedicated Options folders

[PANiXiDA]

What changed

• added an architecture convention requiring every root configuration <Name>Options to reside under Options/<Name>/;
• kept each options class beside its registered IValidateOptions<TOptions> validator;
• moved the existing Identity provider, messaging, cleanup, OAuth, and SMTP options pairs into dedicated subdirectories;
• updated namespaces and all repository references;
• documented the new convention in the architecture tests README.

Why

The existing convention only required an options class and its validator to share a directory. It did not prevent options pairs from being placed directly in an Options directory or outside a dedicated feature-specific subdirectory.

The new rule makes the required layout explicit and enforceable: Options/<Name>/<Name>Options.cs together with <Name>OptionsValidator.cs.

Verification

• dotnet build tests/PANiXiDA.TacticalHeroes.ArchitectureTests/PANiXiDA.TacticalHeroes.ArchitectureTests.csproj --configuration Release --no-restore: passed with 0 warnings and 0 errors;
• dotnet format PANiXiDA.TacticalHeroes.slnx --verify-no-changes --no-restore: passed;
• local tests were not run by request; the full suite and coverage validation are left to CI.

Compatibility

• migrations: none;
• HTTP request and response contracts: unchanged;
• configuration keys and SectionName values: unchanged;
• configuration files: unchanged;
• runtime breaking changes: none;
• source namespaces of the moved Options types changed; all consumers in this repository were updated.