build(plugin): establish build and release pipeline

src/main/java/games/dmg/spigotstealth/SpigotStealthPlugin.java

@@ -0,0 +1,11 @@
+package games.dmg.spigotstealth;
+
+import org.bukkit.plugin.java.JavaPlugin;
+
+/** Bukkit entry point for Spigot Stealth. */
+public final class SpigotStealthPlugin extends JavaPlugin {
+    @Override
+    public void onEnable() {
+        getLogger().info("Spigot Stealth enabled");
+    }
+}