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/events/system/AnvilEventHandler.java

@@ -0,0 +1,66 @@
+package com.tiedup.remake.events.system;
+
+import com.tiedup.remake.core.TiedUpMod;
+import com.tiedup.remake.items.ItemPadlock;
+import com.tiedup.remake.items.base.ILockable;
+import net.minecraft.world.item.ItemStack;
+import net.minecraftforge.event.AnvilUpdateEvent;
+import net.minecraftforge.eventbus.api.SubscribeEvent;
+import net.minecraftforge.fml.common.Mod;
+
+/**
+ * Event handler for anvil-based padlock attachment.
+ *
+ * Phase 20: Padlock via Anvil
+ *
+ * Allows combining a bondage item (ILockable) with a Padlock in the anvil
+ * to make the item "lockable". A lockable item can then be locked with a Key.
+ *
+ * Flow:
+ * - Place ILockable item in left slot
+ * - Place Padlock in right slot
+ * - Output: Same item with lockable=true
+ * - Cost: 1 XP level, consumes 1 padlock
+ */
+@Mod.EventBusSubscriber(modid = TiedUpMod.MOD_ID)
+public class AnvilEventHandler {
+
+    @SubscribeEvent
+    public static void onAnvilUpdate(AnvilUpdateEvent event) {
+        ItemStack left = event.getLeft(); // Bondage item
+        ItemStack right = event.getRight(); // Padlock
+
+        // Skip if either slot is empty
+        if (left.isEmpty() || right.isEmpty()) return;
+
+        // Right slot must be a Padlock
+        if (!(right.getItem() instanceof ItemPadlock)) return;
+
+        // Left slot must be ILockable
+        if (!(left.getItem() instanceof ILockable lockable)) return;
+
+        // Check if item can have a padlock attached (tape, slime, vine, web cannot)
+        if (!lockable.canAttachPadlock()) {
+            return; // Item type cannot have padlock
+        }
+
+        // Item must not already have a padlock attached
+        if (lockable.isLockable(left)) {
+            return; // Already has padlock
+        }
+
+        // Create result: copy of left with lockable=true
+        ItemStack result = left.copy();
+        lockable.setLockable(result, true);
+
+        // Set anvil output
+        event.setOutput(result);
+        event.setCost(1); // 1 XP level cost
+        event.setMaterialCost(1); // Consume 1 padlock
+
+        TiedUpMod.LOGGER.debug(
+            "[AnvilEventHandler] Padlock attachment preview: {} + Padlock",
+            left.getDisplayName().getString()
+        );
+    }
+}