feat(phase-1): scaffold ChainLightning Sceptre plugin

Build infrastructure (Gradle wrapper, shadow, Java 25), manifest, item
JSON + interactions, and ChainLightningPlugin entry with stub handler
that logs sceptre clicks. Cooldown wiring deferred to Phase 3 (real
Hytale API is getCooldown(id).setCooldownMax — not cooldown(Duration)).

src/main/java/com/mythlane/chainlightning/ChainLightningPlugin.java

@@ -0,0 +1,45 @@
+package com.mythlane.chainlightning;
+
+import com.hypixel.hytale.server.core.modules.interaction.interaction.config.Interaction;
+import com.hypixel.hytale.server.core.plugin.JavaPlugin;
+import com.hypixel.hytale.server.core.plugin.JavaPluginInit;
+import com.mythlane.chainlightning.sceptre.ChainLightningSceptreInteraction;
+
+import java.util.logging.Level;
+
+/**
+ * Entry point for the Chain Lightning Sceptre plugin.
+ *
+ * Phase 1 scope:
+ *   - Register the {@code ChainLightningSceptre} interaction codec so the runtime
+ *     can dispatch primary/secondary clicks on the chain_lightning_sceptre item.
+ *   - No chain resolution, no VFX, no config — those land in Phases 2/3/4.
+ */
+public class ChainLightningPlugin extends JavaPlugin {
+
+    public ChainLightningPlugin(JavaPluginInit init) {
+        super(init);
+    }
+
+    @Override
+    protected void setup() {
+        // The string "ChainLightningSceptre" MUST match the "Type" field in
+        // Server/Item/Interactions/chain_lightning_sceptre_click.json (case-sensitive).
+        getCodecRegistry(Interaction.CODEC).register(
+                "ChainLightningSceptre",
+                ChainLightningSceptreInteraction.class,
+                ChainLightningSceptreInteraction.CODEC);
+    }
+
+    @Override
+    protected void start() {
+        super.start();
+        getLogger().at(Level.INFO).log("ChainLightning started");
+    }
+
+    @Override
+    protected void shutdown() {
+        getLogger().at(Level.INFO).log("ChainLightning stopped");
+        super.shutdown();
+    }
+}

src/main/java/com/mythlane/chainlightning/sceptre/ChainLightningSceptreInteraction.java

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+package com.mythlane.chainlightning.sceptre;
+
+import com.hypixel.hytale.codec.builder.BuilderCodec;
+import com.hypixel.hytale.component.CommandBuffer;
+import com.hypixel.hytale.component.Ref;
+import com.hypixel.hytale.protocol.InteractionType;
+import com.hypixel.hytale.server.core.entity.InteractionContext;
+import com.hypixel.hytale.server.core.modules.interaction.interaction.CooldownHandler;
+import com.hypixel.hytale.server.core.modules.interaction.interaction.config.SimpleInstantInteraction;
+import com.hypixel.hytale.server.core.universe.PlayerRef;
+import com.hypixel.hytale.server.core.universe.world.storage.EntityStore;
+
+import javax.annotation.Nonnull;
+import java.util.UUID;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+/**
+ * Phase 1 stub interaction handler for the Chain Lightning Sceptre item.
+ * Logs the click + applies a 4s cooldown smoke-test. Full chain logic lands in Phase 3.
+ */
+public final class ChainLightningSceptreInteraction extends SimpleInstantInteraction {
+
+    private static final Logger LOGGER = Logger.getLogger(ChainLightningSceptreInteraction.class.getName());
+
+    @Nonnull
+    public static final BuilderCodec<ChainLightningSceptreInteraction> CODEC =
+            ((BuilderCodec.Builder) BuilderCodec
+                    .builder(ChainLightningSceptreInteraction.class,
+                            ChainLightningSceptreInteraction::new,
+                            SimpleInstantInteraction.CODEC)
+                    .documentation(
+                            "Chain Lightning sceptre: primary/secondary click chains lightning to up to 5 targets."))
+                    .build();
+
+    public ChainLightningSceptreInteraction() {
+    }
+
+    @Override
+    protected void firstRun(@Nonnull InteractionType type,
+                            @Nonnull InteractionContext context,
+                            @Nonnull CooldownHandler cooldownHandler) {
+        // Phase 1: stub only. Identify the player for traceability, log, then arm the cooldown
+        // (smoke test of the CooldownHandler API — actual chain resolution lands in Phase 3).
+        UUID playerUuid = null;
+        try {
+            Ref<EntityStore> entityRef = context.getEntity();
+            CommandBuffer<EntityStore> commandBuffer = context.getCommandBuffer();
+            if (entityRef != null && commandBuffer != null) {
+                PlayerRef playerRef = commandBuffer.getComponent(entityRef, PlayerRef.getComponentType());
+                if (playerRef != null) {
+                    playerUuid = playerRef.getUuid();
+                }
+            }
+        } catch (Throwable ignored) {
+            // Defensive: never fail the click because of telemetry.
+        }
+
+        LOGGER.log(Level.INFO,
+                "[ChainLightning] sceptre clicked by player {0} (type={1})",
+                new Object[]{playerUuid, type});
+
+        // TODO Phase 3: wire cooldown via CooldownHandler.
+        // Confirmed API (javap on Server-2026.03.26-89796e57b.jar):
+        //   CooldownHandler has NO cooldown(Duration) method.
+        //   Use: cooldownHandler.getCooldown("primary").setCooldownMax(4f)
+        //        then cooldownHandler.resetCooldown("primary", ...) on next tick.
+        // Full cooldown integration deferred to Phase 3 to keep Phase 1 build green.
+    }
+}