WS14 — Oracle 19c: tests, regression, QA/PR review

[wz-gsa]

Part of #519.

Goal

Add Oracle without regressing existing engines.

Test categories

• Unit: Oracle plan validation, DB-name formatting, username/password validation, parameter-group generation, option-group generation, log-export config, binding payload shape.
• Regression: Postgres/MySQL plans, parameter-group + option-group tests, Redis/OpenSearch unaffected.
• Negative: invalid Oracle DB names; STIG-weakening param overrides; public Oracle DB rejected by default; missing license model; unsupported GovCloud option.

Commands

go test ./..., go test ./services/rds/..., cd cmd/tasks && go test ./.... Mocked RDS client only — no live AWS in unit tests. Add QA + multi-voter PR review before merge.

Acceptance criteria

• All existing tests pass; Oracle-specific tests added; mocked RDS covers Oracle create/modify.