Prepare v0.3.0 release - #28

Summary

• declare package and citation version 0.3.0
• pin the generated PyPI description and stable-release links to v0.3.0
• mark the RecoveryBench quality record validated and close the pre-tag checklist
• keep post-tag OIDC/public-artifact verification explicitly pending

Validation

• Ruff check and format check
• mypy src/miniverl
• 1408 non-GPU/non-network tests, 6 deselected, 86.68% branch coverage
• 85 packaging tests and Markdown/link checks
• one 0.3.0 wheel and one sdist built in an isolated directory; Twine passed both
• release metadata/tag preflight and PyPI README byte check
• frozen RecoveryBench and legacy calculator hashes unchanged

Scope

Release metadata only. RecoveryBench implementation and frozen scientific artifacts are unchanged. The tag will be created only after this PR and synchronized main are green.