chore(release): 0.13.0

[svyatov]

What changed

Folds the accumulated Unreleased section into ## [0.13.0] - 2026-08-07, adds its compare link, and bumps version in the three plugin manifests.

Why this way

MINOR applies because R-PUB-02 now requires Maven Central credentials to become available only after a native forge publication gate. A repository that relied on a USER_MANAGED Portal stop can pass 0.12.0 and fail 0.13.0.

The README Versioning section assigns incompatible changes to MINOR releases while the version remains below 1.0.0.

Verification

• bun run typecheck
• bun test, 327 tests passed
• bun run validate, 0 errors and 0 warnings
• bash tests/test-check-drift.sh, 12 tests passed
• bash scripts/check-drift.sh
• bun scripts/check-ecosystems.mjs, 11 ecosystems x 7 skills present
• skillspector scan ./skills/ --no-llm --format json
• bun run build in site/, 114 pages built
• node skills/oss-changelog/scripts/release-notes.mjs v0.13.0
• git diff --check

Affects

Rule or skill	Change
none	release bookkeeping only