Add dependency-aware release versioning

[clelange]

Summary

• derive the repository release base from the pinned mkdocs-material==X.Y.Z version
• increment a fourth version component for plugin-only releases
• preserve exact four-component tags by passing computed names and tags directly to Release Drafter
• migrate the Release Drafter configuration away from deprecated category and resolver fields
• scope draft updates to Python requirements changes and serialize concurrent runs

Why

Release Drafter v7 warns about the legacy category, exclusion, and version-resolver fields. Its SemVer resolver also coerces tags such as 9.7.7.1 to three components, so it cannot natively express this repository's existing sub-patch release convention.

The new standard-library resolver compares the current core pin with all published stable package tags. Core updates draft the exact upstream version, while unchanged core versions advance the fourth component. Unpublished plugin changes continue to coalesce into the same draft.

Impact

Releases remain drafts and are still published manually. Publishing continues to trigger the existing multi-architecture image workflow. Non-requirements pushes no longer update the release draft, though their changes can appear when the next dependency release is drafted.

Validation

• python3 -m unittest discover -s .github/scripts -p 'test_*.py' — 12 tests pass
• YAML parsing and workflow/config semantic assertions pass
• live resolution against published repository tags returns version=9.7.7
• the current stable draft count is one
• git diff --check passes