refactor: migrate package from com.loki to dev.loki

- Change base package from com.loki to dev.loki across all Java files
- Update plugin.yml main class path
- Fix ConfigParseException imports in test files
- Update build.gradle.kts relocate patterns
- Add missing imports in ConfigLoaderTest.java
- Update TODO.md with current status

BREAKING CHANGE: Package namespace changed from com.loki to dev.loki

src/main/java/dev/loki/lomines/gui/package-info.java

@@ -0,0 +1,13 @@
+/**
+ * GUI editors for mine configuration.
+ * <p>
+ * This package contains graphical user interface implementations using LoAPI's InventoryGUI:
+ * <ul>
+ *   <li>{@code MinesEditor} - List view of all mines</li>
+ *   <li>{@code MineEditor} - Main menu for a specific mine</li>
+ *   <li>{@code MineContentsEditor} - Editor for mine block contents</li>
+ *   <li>{@code MineRewardsEditor} - List view of mine rewards</li>
+ *   <li>{@code MineRewardEditor} - Editor for a specific reward</li>
+ * </ul>
+ */
+package dev.loki.lomines.gui;