Clean repo for open source release

Remove build artifacts, dev tool configs, unused dependencies,
and third-party source dumps. Add proper README, update .gitignore,
clean up Makefile.

src/main/java/com/tiedup/remake/mixin/MixinMCAVillagerLeash.java

@@ -0,0 +1,84 @@
+package com.tiedup.remake.mixin;
+
+import com.tiedup.remake.compat.mca.MCACompat;
+import com.tiedup.remake.v2.BodyRegionV2;
+import com.tiedup.remake.items.base.ItemCollar;
+import com.tiedup.remake.state.IBondageState;
+import net.minecraft.world.entity.LivingEntity;
+import net.minecraft.world.entity.Mob;
+import net.minecraft.world.entity.player.Player;
+import net.minecraft.world.item.ItemStack;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.Pseudo;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfoReturnable;
+
+/**
+ * Mixin to allow vanilla leash attachment to MCA villagers when tied or collar owner.
+ *
+ * <p>By default, MCA villagers cannot be leashed. This mixin overrides
+ * the canBeLeashed check to allow leashing when:
+ * <ul>
+ *   <li>The villager is tied up (any bind), OR</li>
+ *   <li>The player is a collar owner</li>
+ * </ul>
+ *
+ * <p>Uses @Pseudo annotation - mixin is optional and will be skipped if MCA is not installed.
+ */
+@Pseudo
+@Mixin(targets = "forge.net.mca.entity.VillagerEntityMCA", remap = false)
+public class MixinMCAVillagerLeash {
+
+    /**
+     * Override canBeLeashed to allow TiedUp leash mechanics.
+     *
+     * <p>The canBeLeashed method is a vanilla method (remapped), so we use remap = true.
+     *
+     * @param player The player trying to leash
+     * @param cir Callback info for returning the result
+     */
+    @Inject(
+        method = "canBeLeashed",
+        at = @At("HEAD"),
+        cancellable = true,
+        remap = true
+    )
+    private void tiedup$overrideCanBeLeashed(
+        Player player,
+        CallbackInfoReturnable<Boolean> cir
+    ) {
+        LivingEntity entity = (LivingEntity) (Object) this;
+        IBondageState state = MCACompat.getKidnappedState(entity);
+
+        // No TiedUp state - let vanilla/MCA handle it
+        if (state == null) {
+            return;
+        }
+
+        // Already leashed - cannot leash again
+        if (entity instanceof Mob mob && mob.isLeashed()) {
+            cir.setReturnValue(false);
+            return;
+        }
+
+        // Can be leashed if tied up
+        if (state.isTiedUp()) {
+            cir.setReturnValue(true);
+            return;
+        }
+
+        // Can be leashed if player is collar owner
+        if (state.hasCollar()) {
+            ItemStack collar = state.getEquipment(BodyRegionV2.NECK);
+            if (collar.getItem() instanceof ItemCollar collarItem) {
+                if (collarItem.getOwners(collar).contains(player.getUUID())) {
+                    cir.setReturnValue(true);
+                    return;
+                }
+            }
+        }
+
+        // Default: let MCA handle it (usually returns false)
+    }
+}