fix(registry): recover package publication

[smackgg]

What changed

• bump the Xiaoyunque Plugin from 0.3.0 to 0.3.1 because the failed 0.3.0 tag is immutable
• advance the Registry sequence from 19 to 20
• update the package lock and release expectation

Why

The previous FFmpeg and Xiaoyunque package tags were created before the workspace-aware publishing fix and failed verification. No successful package Release followed the main-branch fix, so GitHub Pages stayed at Registry sequence 8 while Convax clients already held sequence 17. Skill details consequently failed the anti-rollback check.

Verification

• bun install --frozen-lockfile --ignore-scripts
• CONVAX_FFMPEG_SOURCE_ARCHIVE=<verified ffmpeg-8.1.2.tar.xz> bun run check
• 15 packages validated at Registry sequence 20
• 139 workspace tests and 52 repository tooling tests passed
• both FFmpeg and Xiaoyunque companion targets built and verified
• deterministic Registry and Showcase builds succeeded