ci: Auto-update manifest.json on new releases

[enyineer]

Summary

Adds a GitHub Actions workflow that automatically updates manifest.json whenever a GitHub Release is published, edited, or deleted — no more manual edits to the versions array.

How It Works

The workflow triggers on three release event types:

published — New version added

1. Extracts the version from the release tag (e.g. 1.7.0 → 1.7.0.0), stripping any v prefix and appending .0 if needed
2. Reads targetAbi from the Jellyfin.Controller PackageReference in backend/Moonfin.Server.csproj
3. Downloads the Moonfin.Server-*.zip asset attached to the release and computes its MD5 checksum (uppercase)
4. Sanitizes the changelog — strips markdown formatting (badges, bold, links, headers, code ticks, horizontal rules) from the release body to produce clean plain text suitable for Jellyfin's UI
5. Formats the timestamp from the release created_at field
6. Prepends a new version entry to .[0].versions in manifest.json using jq
7. Commits and pushes the updated manifest back to the default branch

edited — Version entry updated

When a release is edited (e.g. release notes changed), the workflow upserts the version entry — it removes the existing entry with the matching version and prepends a freshly built one. This also handles edge cases where assets were re-uploaded.

deleted — Version entry removed

When a release is deleted, the workflow removes the matching version entry from the versions array.

Field Mapping

Field	Source
version	Release tag (e.g. 1.7.0 → 1.7.0.0)
changelog	Release body, sanitized to plain text
targetAbi	Jellyfin.Controller version from .csproj + .0
sourceUrl	Moonfin.Server-*.zip asset download URL from the release
checksum	MD5 of the downloaded zip (uppercase)
timestamp	Release created_at → YYYY-MM-DDTHH:MM:SS
dependencies	Always []

Changelog Sanitization

GitHub release bodies use rich markdown (headers, bold, badges, links, code ticks), but Jellyfin renders the changelog as plain text. The workflow automatically strips markdown to produce clean output:

Before (raw release body):

## Moonfin v1.6.0 Release Notes [![github](https://img.shields.io/...)](...)
### Bug Fixes
- **Fixed proxy navigation** — Search, sidebar links...
- `MDBList` batch task refactored

After (sanitized for manifest):

Bug Fixes
- Fixed proxy navigation — Search, sidebar links...
- MDBList batch task refactored

Benefits

• Zero manual work — just write your release notes, attach the zip, and publish
• No drift — manifest stays in sync with releases automatically
• Full lifecycle — handles new releases, edits to release notes, and release deletions
• Clean changelogs — markdown is automatically stripped to plain text for Jellyfin's UI
• Injection-safe — all GitHub expression interpolation uses env: variables
• Stable asset detection — specifically matches Moonfin.Server-*.zip rather than any .zip
• Race-condition safe — uses git pull --rebase before push

Tested

All event types and changelog sanitization tested on a fork:

Event	Run	Result
published	22817606235	✅ Version prepended correctly
edited	22817618274	✅ Changelog updated in-place
deleted	22817634272	✅ Version entry removed
published + sanitization	22817876277	✅ Markdown stripped to plain text