docs: prepare OpenSSF Silver readiness evidence

[TFT444]

Summary

Builds the repository-controlled foundation for OpenSSF Best Practices Silver issue #199 without claiming criteria that require owner or operational confirmation.

Governance and public evidence

• adds governance, maintainer responsibility, continuity, 12-month roadmap, support and upgrade documentation
• documents security requirements, threat model, trust boundaries and a structured assurance case
• adds release-security, accessibility/i18n and vulnerability-credit records
• adds a criterion-by-criterion Silver evidence register separating ready evidence, gaps, owner actions and likely N/A answers
• records a preliminary six-month regression-test audit

Technical readiness

• raises the API/scanner coverage gate from 25% to the Silver requirement of 80%
• adds direct AzureClient management-wrapper tests; measured local coverage is 82.2%
• changes frontend lint to fail on warnings and resolves the four existing React hook warnings
• reconciles public documentation and website inventory with the current 51 rules and 51 playbooks
• updates supported-version guidance

Owner actions deliberately not claimed

The following remain open for the project lead:

• confirm real access continuity and bus factor, not only documented roles
• approve and enforce DCO or another contribution authorization mechanism
• select and operate release signing/attestation and important tag signing
• confirm vulnerability acknowledgement history and regression-test evidence
• complete accessibility, input-validation, algorithm-agility and reproducibility reviews
• enter reviewed evidence into the official OpenSSF assessment

Validation

• 382 tests passed with 82.2% API/scanner statement coverage (--cov-fail-under=80)
• Ruff passes
• frontend ESLint passes with zero warnings
• frontend production build passes
• website security tests pass
• all workflow YAML parses successfully
• website and repository rule inventories both report 51 rules
• git diff --check passes

Advances #199

[github-actions]

Dependency Review

✅ No vulnerabilities or license issues or OpenSSF Scorecard issues found.

Scanned Files

None