Add Holograms integration and Sub-GUI editors

Holograms:
- HologramManager with auto-detection of HolographicDisplays/DecentHolograms
- HologramProvider interface and implementations
- HologramConfig for per-mine configuration
- /lm hologram <mine> [on|off] command
- Updates every second showing mine name, fill %, progress bar, and timer

Sub-GUI Editors:
- BlocksGui - edit block weights with +/- clicks
- BlockMaterialSelectionGui - paginated material picker
- ResetGui - configure reset interval, percent trigger, message, commands
- RewardsGui - manage reward entries
- All holders moved to gui/mine/holder/
- Editors moved to gui/mine/edit/
- Main GUI (MineEditGui) moved to gui/mine/main/

Package structure reorganized to maintain max 6 files per folder.

src/main/java/dev/loki/lomines/RegistrationManager.java

@@ -1,6 +1,7 @@
 package dev.loki.lomines;
 
 import dev.loki.lomines.command.admin.AdminCommands;
+import dev.loki.lomines.command.admin.HologramCommands;
 import dev.loki.lomines.command.admin.MaskCommands;
 import dev.loki.lomines.command.admin.StatsCommands;
 import dev.loki.lomines.command.common.LoMinesTabCompleter;
@@ -29,6 +30,7 @@ final class RegistrationManager {
         commandManager.register(new PlayerCommands(plugin));
         commandManager.register(new StatsCommands(plugin));
         commandManager.register(new MaskCommands(plugin));
+        commandManager.register(new HologramCommands(plugin));
 
         plugin.loLogger().info("Commands registered");
     }