feat(D-01): instantiate ComponentHolder per item definition on reload

Add a parallel COMPONENT_HOLDERS volatile cache to DataDrivenItemRegistry,
rebuilt from raw componentConfigs every time definitions are loaded via
reload() or mergeAll(). Cleared alongside DEFINITIONS in clear().

Two accessor methods allow looking up a ComponentHolder by ItemStack
(reads tiedup_item_id NBT) or by ResourceLocation directly.

src/main/java/com/tiedup/remake/v2/bondage/datadriven/DataDrivenItemRegistry.java

@@ -1,7 +1,12 @@
 package com.tiedup.remake.v2.bondage.datadriven;
 
+import com.google.gson.JsonObject;
+import com.tiedup.remake.v2.bondage.component.ComponentHolder;
+import com.tiedup.remake.v2.bondage.component.ComponentType;
+import com.tiedup.remake.v2.bondage.component.IItemComponent;
 import java.util.Collection;
 import java.util.Collections;
+import java.util.EnumMap;
 import java.util.HashMap;
 import java.util.Map;
 import net.minecraft.nbt.CompoundTag;
@@ -34,6 +39,13 @@ public final class DataDrivenItemRegistry {
         DataDrivenItemDefinition
     > DEFINITIONS = Map.of();
 
+    /**
+     * Parallel cache of instantiated component holders, keyed by item definition ID.
+     * Rebuilt every time DEFINITIONS changes.
+     */
+    private static volatile Map<ResourceLocation, ComponentHolder>
+        COMPONENT_HOLDERS = Map.of();
+
     private DataDrivenItemRegistry() {}
 
     /**
@@ -46,6 +58,7 @@ public final class DataDrivenItemRegistry {
         Map<ResourceLocation, DataDrivenItemDefinition> newDefs
     ) {
         DEFINITIONS = Collections.unmodifiableMap(new HashMap<>(newDefs));
+        COMPONENT_HOLDERS = buildComponentHolders(DEFINITIONS);
     }
 
     /**
@@ -66,6 +79,7 @@ public final class DataDrivenItemRegistry {
         );
         merged.putAll(newDefs);
         DEFINITIONS = Collections.unmodifiableMap(merged);
+        COMPONENT_HOLDERS = buildComponentHolders(DEFINITIONS);
     }
 
     /**
@@ -111,5 +125,65 @@ public final class DataDrivenItemRegistry {
      */
     public static void clear() {
         DEFINITIONS = Map.of();
+        COMPONENT_HOLDERS = Map.of();
+    }
+
+    // ===== COMPONENT HOLDERS =====
+
+    /**
+     * Get the ComponentHolder for a data-driven item stack.
+     *
+     * @param stack the ItemStack to inspect
+     * @return the holder, or null if the stack is not data-driven or has no definition
+     */
+    @Nullable
+    public static ComponentHolder getComponents(ItemStack stack) {
+        DataDrivenItemDefinition def = get(stack);
+        if (def == null) return null;
+        return COMPONENT_HOLDERS.get(def.id());
+    }
+
+    /**
+     * Get the ComponentHolder for a data-driven item by its definition ID.
+     *
+     * @param id the definition ID
+     * @return the holder, or null if not found
+     */
+    @Nullable
+    public static ComponentHolder getComponents(ResourceLocation id) {
+        return COMPONENT_HOLDERS.get(id);
+    }
+
+    /**
+     * Build component holders from a definitions map.
+     * Each definition's raw componentConfigs are instantiated via
+     * {@link ComponentType#create(JsonObject)}.
+     */
+    private static Map<ResourceLocation, ComponentHolder> buildComponentHolders(
+        Map<ResourceLocation, DataDrivenItemDefinition> definitions
+    ) {
+        Map<ResourceLocation, ComponentHolder> holders = new HashMap<>();
+        for (Map.Entry<ResourceLocation, DataDrivenItemDefinition> entry :
+            definitions.entrySet()) {
+            DataDrivenItemDefinition def = entry.getValue();
+            Map<ComponentType, IItemComponent> components =
+                new EnumMap<>(ComponentType.class);
+            if (def.componentConfigs() != null) {
+                for (Map.Entry<ComponentType, JsonObject> compEntry :
+                    def.componentConfigs().entrySet()) {
+                    components.put(
+                        compEntry.getKey(),
+                        compEntry.getKey().create(compEntry.getValue())
+                    );
+                }
+            }
+            holders.put(
+                entry.getKey(),
+                components.isEmpty()
+                    ? ComponentHolder.EMPTY
+                    : new ComponentHolder(components)
+            );
+        }
+        return Collections.unmodifiableMap(holders);
     }
 }