fabric: Equipping DeepSeek Harness with Minecraft-style Mixin Hooks

Fabric is a DSH community plugin maintained by omdsh-dev, similar to the load-time hook processor for Minecraft Fabric. It adopts a three-pack splitting mechanism, rewriting target functions with trusted code without modifying the original source code of the target. The directory page command is `dsh plugin add github:omdsh-dev/fabric`; the English README also recommends the released `pkg.tgz`. It is disabled by default and needs to be enabled before launching with `fabric-dsh`.