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/block/BlockSetter.java

@@ -0,0 +1,37 @@
+package dev.loki.lomines.block;
+
+import dev.loki.lomines.util.location.Cuboid;
+import org.bukkit.Location;
+
+import java.util.List;
+import java.util.function.IntConsumer;
+
+/**
+ * Abstract base class for block setting strategies.
+ * Provides a template for filling mine regions with blocks.
+ *
+ * <p>Implementations:</p>
+ * <ul>
+ *   <li>BukkitBlockSetter - For vanilla Minecraft blocks</li>
+ *   <li>OraxenBlockSetter - For Oraxen custom blocks</li>
+ *   <li>ItemsAdderBlockSetter - For ItemsAdder custom blocks</li>
+ * </ul>
+ *
+ * <p>This is a placeholder that will be fully implemented in task 2.7.</p>
+ */
+public abstract class BlockSetter {
+
+    /**
+     * Fills a cuboid region with blocks asynchronously.
+     * The callback is invoked in the main thread after completion.
+     *
+     * @param region   The region to fill
+     * @param callback Called with the number of blocks set when complete
+     */
+    public abstract void fill(Cuboid region, IntConsumer callback);
+
+    /**
+     * Places random weighted blocks only at the given locations (mask mode).
+     */
+    public abstract void fillAtLocations(List<Location> locations, IntConsumer callback);
+}