Fabric build for Minecraft 1.21.x, would a backport branch be useful?

[StacikM]

Hi! Plan 5.8.x's Fabric module requires Minecraft 26.1+ / Java 25. I run a Velocity network with a Fabric 1.21.11 server and wanted Plan sessions on it, so I built an unofficial variant: the 5.8.3638 core with the Fabric module from 5.7.3306 adapted for 1.21.11 (12 files, 41 insertions / 31 deletions). It's published on my fork (https://github.com/StacikM/Plan/tree/fabric-1.21.11), with the patch against tag 5.8.3638: https://github.com/StacikM/Plan/releases/tag/5.8.3638-mc1.21.11

I've only tested it on one 1.21.11 server (sessions are stored, the mod registers with the proxy), and I haven't run the upstream test suite.

Is a 1.21.x Fabric backport something you'd want upstream, or is dropping it intentional? If you'd like it, I'm happy to open a PR against whichever branch you prefer. If not, no problem — I'll just keep it on my fork.

The patch was generated with AI assistance (Claude Code, Claude Sonnet 5.5), in line with the repo's AGENTS.md.

[AuroraLS3]

I don't have energy to maintain multiple fabric versions so if their api breaks something then versions are dropped.