feat(04-04): add tp subcommand teleporting to region AABB center (CMD-06)

- AbstractPlayerCommand (tp only makes sense for a player caller)
- Pattern mirrors TeleportToCoordinatesCommand:48-68 (read Transform+HeadRotation,
  build Teleport.createForPlayer(pos, bodyRotation).setHeadRotation(headRotation),
  store.addComponent)
- Center computed componentwise: c = (min+max)/2
- Preserves caller body+head rotation (teleport in place, no look change)
- Clear error on unknown region name

src/main/java/com/mythlane/gravityflip/command/GravityFlipTpSubCommand.java

@@ -0,0 +1,104 @@
+package com.mythlane.gravityflip.command;
+
+import com.hypixel.hytale.component.Ref;
+import com.hypixel.hytale.component.Store;
+import com.hypixel.hytale.math.vector.Vector3d;
+import com.hypixel.hytale.math.vector.Vector3f;
+import com.hypixel.hytale.server.core.Message;
+import com.hypixel.hytale.server.core.command.system.CommandContext;
+import com.hypixel.hytale.server.core.command.system.arguments.system.RequiredArg;
+import com.hypixel.hytale.server.core.command.system.arguments.types.ArgTypes;
+import com.hypixel.hytale.server.core.command.system.basecommands.AbstractPlayerCommand;
+import com.hypixel.hytale.server.core.modules.entity.component.HeadRotation;
+import com.hypixel.hytale.server.core.modules.entity.component.TransformComponent;
+import com.hypixel.hytale.server.core.modules.entity.teleport.Teleport;
+import com.hypixel.hytale.server.core.universe.PlayerRef;
+import com.hypixel.hytale.server.core.universe.world.World;
+import com.hypixel.hytale.server.core.universe.world.storage.EntityStore;
+import com.mythlane.gravityflip.GravityFlipPlugin;
+import com.mythlane.gravityflip.region.GravityFlipRegion;
+
+import javax.annotation.Nonnull;
+
+/**
+ * {@code /gravityflip tp <name>} — téléporte le joueur appelant au centre de
+ * l'AABB d'une région Gravity Flip. Outil debug/builder (CMD-06).
+ *
+ * <p>Étend {@link AbstractPlayerCommand} : tp ne fait sens que pour un joueur,
+ * la base class gère automatiquement le message "must be player" pour un appel console.
+ *
+ * <p>Pattern Teleport copié ligne-à-ligne sur
+ * {@code com.hypixel.hytale.builtin.teleport.commands.teleport.variant.TeleportToCoordinatesCommand}
+ * (lignes 48-68) :
+ * <ol>
+ *   <li>Lire {@link TransformComponent} (rotation corps) et {@link HeadRotation}
+ *       (rotation tête) pour préserver l'orientation du joueur.</li>
+ *   <li>Calculer le centre componentwise : {@code c = (min + max) / 2}.</li>
+ *   <li>Construire via {@code Teleport.createForPlayer(pos, rotation).setHeadRotation(...)}.</li>
+ *   <li>{@code store.addComponent(ref, Teleport.getComponentType(), teleport)} —
+ *       le {@code TeleportSystem} du core consomme le composant au prochain tick.</li>
+ * </ol>
+ *
+ * <p>T-04-04-02 : permission auto-générée {@code mythlane.gravityflip.command.gravityflip.tp}
+ * sert de gate. Pas de restriction GameMode v1 (builder tool).
+ */
+public final class GravityFlipTpSubCommand extends AbstractPlayerCommand {
+
+    private final GravityFlipPlugin plugin;
+
+    private final RequiredArg<String> nameArg =
+            this.withRequiredArg("name", "Nom de la région cible", ArgTypes.STRING);
+
+    public GravityFlipTpSubCommand(GravityFlipPlugin plugin) {
+        super("tp", "Téléporte au centre d'une région Gravity Flip");
+        this.plugin = plugin;
+    }
+
+    @Override
+    protected void execute(@Nonnull CommandContext ctx,
+                           @Nonnull Store<EntityStore> store,
+                           @Nonnull Ref<EntityStore> ref,
+                           @Nonnull PlayerRef playerRef,
+                           @Nonnull World world) {
+        String name = nameArg.get(ctx);
+        GravityFlipRegion target = null;
+        for (GravityFlipRegion r : plugin.regions().all()) {
+            if (r.getName().equals(name)) {
+                target = r;
+                break;
+            }
+        }
+        if (target == null) {
+            ctx.sendMessage(Message.raw("[gravityflip] Région '" + name + "' introuvable."));
+            return;
+        }
+
+        Vector3d mn = target.getMin();
+        Vector3d mx = target.getMax();
+        double cx = (mn.x + mx.x) / 2.0;
+        double cy = (mn.y + mx.y) / 2.0;
+        double cz = (mn.z + mx.z) / 2.0;
+
+        TransformComponent tc = store.getComponent(ref, TransformComponent.getComponentType());
+        if (tc == null) {
+            ctx.sendMessage(Message.raw(
+                    "[gravityflip] TransformComponent manquant — tp impossible."));
+            return;
+        }
+        HeadRotation hr = store.getComponent(ref, HeadRotation.getComponentType());
+
+        // Préserve l'orientation courante : body rotation depuis Transform, head rotation
+        // si disponible (sinon on laisse la default côté Teleport.createForPlayer).
+        Vector3f bodyRotation = tc.getRotation().clone();
+        Teleport teleport = Teleport.createForPlayer(
+                new Vector3d(cx, cy, cz), bodyRotation);
+        if (hr != null) {
+            teleport = teleport.setHeadRotation(hr.getRotation().clone());
+        }
+        store.addComponent(ref, Teleport.getComponentType(), teleport);
+
+        ctx.sendMessage(Message.raw(String.format(
+                "[gravityflip] Téléporté au centre de '%s' : (%.0f,%.0f,%.0f)",
+                name, cx, cy, cz)));
+    }
+}