feat: add listing endpoints for secrets, transit, and tokenization keys

[allisson]

This commit introduces comprehensive listing capabilities across all core cryptographic modules, supporting pagination via limit and offset query parameters.

Key additions:

• Secrets Module:

  • Added GET /v1/secrets HTTP handler.
  • Implemented List usecase operations with metrics decorators.
  • Added List methods to both PostgreSQL and MySQL repositories.
  • Created ListSecretsResponse DTO for consistent API responses.

• Transit Module:

  • Added GET /v1/transit/keys HTTP handler.
  • Implemented List usecase operations with metrics decorators.
  • Added List methods to both PostgreSQL and MySQL repositories.
  • Created ListTransitKeysResponse DTO.

• Tokenization Module:

  • Added GET /v1/tokenization/keys HTTP handler.
  • Implemented List usecase operations with metrics decorators.
  • Added List methods to PostgreSQL and MySQL repositories.
  • Created ListTokenizationKeysResponse DTO.

• Routing & Config:

  • Registered the new GET endpoints in internal/http/server.go.
  • Bumped application version to 0.16.0 in cmd/app/main.go.

• Documentation & Release Prep:

  • Documented new routes, DTOs, and parameters in docs/openapi.yaml.
  • Updated API markdown documentation in docs/api/data/.
  • Updated CHANGELOG.md, docs/releases/RELEASES.md, and compatibility matrices.
  • Refreshed documentation metadata (docs/metadata.json).

• Testing:

  • Maintained strict test coverage matching project guidelines.
  • Added fully-native integration tests for all new MySQL and PostgreSQL repository List methods.
  • Included unit tests for all new DTO mappers, usecases, and HTTP handlers.