Phase 2.2 : fork mesh/transformer/ (vanilla PlayerModel → SkinnedMesh)

COPY verbatim EF + rewrite imports :
- rig/mesh/transformer/VanillaModelTransformer.java (~700 LOC)
  Transformer principal : bake PlayerModel vanilla / HumanoidModel → SkinnedMesh biped
  EF. Utilise les PartTransformer (HEAD/ARM/LEG/CHEST) avec AABB cover area.
- rig/mesh/transformer/HumanoidModelTransformer.java (~70 LOC)
  Base abstract commune aux transformers humanoïdes.
- rig/mesh/transformer/HumanoidModelBaker.java (~115 LOC)
  Entry point bake() + export JSON + registry MODEL_TRANSFORMERS.

L'ancienne stub de VanillaMeshPartDefinition (record 55 LOC) est remplacée par
la vraie record dans le fork — API identique (of(partName), of(partName, path,
invertedParentTransform, root)).

Ajouté mixin accessor :
- rig/mixin/client/MixinAgeableListModel.java (@Invoker pour headParts/bodyParts
  sur AgeableListModel).
- src/main/resources/tiedup-rig.mixins.json (nouveau mixin config, package
  com.tiedup.remake.rig.mixin).
- build.gradle : args '-mixin.config=tiedup-rig.mixins.json' dans client+server
  run configs.
- META-INF/mods.toml : [[mixins]] config="tiedup-rig.mixins.json"

Logger EpicFightMod.LOGGER → TiedUpRigConstants.LOGGER dans HumanoidModelBaker.
Packages correctement rewrités par scripts/rig-rewrite-imports.sh. Compile
BUILD SUCCESSFUL maintenu.

src/main/resources/META-INF/mods.toml

@@ -81,6 +81,9 @@ config="tiedup.mixins.json"
 [[mixins]]
 config="tiedup-compat.mixins.json"
 
+[[mixins]]
+config="tiedup-rig.mixins.json"
+
 # Features are specific properties of the game environment, that you may want to declare you require. This example declares
 # that your mod requires GL version 3.2 or higher. Other features will be added. They are side aware so declaring this won't
 # stop your mod loading on the server for example.

src/main/resources/tiedup-rig.mixins.json

@@ -0,0 +1,14 @@
+{
+  "required": true,
+  "minVersion": "0.8",
+  "package": "com.tiedup.remake.rig.mixin",
+  "compatibilityLevel": "JAVA_17",
+  "refmap": "tiedup-rig.refmap.json",
+  "mixins": [],
+  "client": [
+    "client.MixinAgeableListModel"
+  ],
+  "injectors": {
+    "defaultRequire": 1
+  }
+}