feat(gui): add mine editor GUI system

New GUI classes:
- MineEditGui.java - main editor with navigation to sub-editors
- MineEditGuiHolder.java - inventory holder for editor
- ConfirmDeleteGui.java - confirmation dialog for mine deletion
- ConfirmDeleteGuiHolder.java - inventory holder for confirmation
- MineEditGuiListener.java - handles clicks in editor GUIs

Updated:
- AdminCommands.java - add /lm edit <mine> command
- RegistrationManager.java - register MineEditGuiListener
- plugin.yml - add lomines.admin.edit permission

Features:
- Visual editor showing mine configuration sections
- Blocks, Regions, Reset, Rewards, Teleport, UI sections
- Save and Delete actions with confirmation
- Info panel showing mine status (blocks, volume, percent)

Sub-editors (placeholder, to be implemented):
- BlockEditGui - edit block types and weights
- ResetEditGui - edit reset interval and triggers
- RewardEditGui - edit mining rewards
- TeleportEditGui - edit teleport on reset
- UIEditGui - edit action bar settings

src/main/java/dev/loki/lomines/command/AdminCommands.java

@@ -3,20 +3,23 @@ package dev.loki.lomines.command;
 import dev.loki.lomines.LoMinesPlugin;
 import dev.loki.lomines.core.Mine;
 import dev.loki.lomines.core.Mines;
+import dev.loki.lomines.gui.MineEditGui;
 import dev.loki.lomines.util.ErrorHandler;
 import dev.loki.lomines.util.MessageFormatter;
 import dev.lolib.commands.annotation.Arg;
 import dev.lolib.commands.annotation.Command;
 import dev.lolib.commands.annotation.Subcommand;
 import net.kyori.adventure.text.Component;
+import net.kyori.adventure.text.format.NamedTextColor;
 import org.bukkit.command.CommandSender;
+import org.bukkit.entity.Player;
 
 import java.io.IOException;
 import java.util.Collection;
 
 /**
  * Admin commands for mine management.
- * Provides commands for creating, deleting, resetting, reloading, and listing mines.
+ * Provides commands for creating, deleting, resetting, reloading, listing, and editing mines.
  */
 @Command(value = "lm", permission = "lomines.use")
 public class AdminCommands {
@@ -43,6 +46,10 @@ public class AdminCommands {
             sender.sendMessage(Component.text(
                     "Edit selection & contents in plugins/LoMines/mines/" + name + ".yml — "
                             + "for shape-based ore (not full cuboid), paint mask.marker blocks, then: /lm maskscan " + name));
+            if (sender instanceof Player player) {
+                sender.sendMessage(Component.text(
+                        "Or use: /lm edit " + name + " to open GUI editor", NamedTextColor.YELLOW));
+            }
         } catch (IllegalArgumentException e) {
             errorHandler.handleNotFound(sender, "Mine already exists", name);
         } catch (IOException e) {
@@ -68,6 +75,26 @@ public class AdminCommands {
         }
     }
 
+    /**
+     * Opens the GUI editor for a mine.
+     * Usage: /lm edit <mine>
+     */
+    @Subcommand(value = "edit", permission = "lomines.admin.edit")
+    public void edit(CommandSender sender, @Arg("mine") String mineName) {
+        if (!(sender instanceof Player player)) {
+            sender.sendMessage(Component.text("This command can only be used by players!", NamedTextColor.RED));
+            return;
+        }
+
+        Mine mine = mines.find(mineName).orElse(null);
+        if (mine == null) {
+            errorHandler.handleNotFound(sender, "Mine", mineName);
+            return;
+        }
+
+        MineEditGui.open(plugin, player, mineName);
+    }
+
     /**
      * Resets a mine by refilling all its regions.
      * Usage: /lm reset <mine> [silent]
@@ -135,4 +162,4 @@ public class AdminCommands {
 
         return String.format("(%d/%d blocks, %.1f%%)", blocks, total, percent);
     }
-}
+}