feat: add showcase region on first run to enhance user experience

- Implemented a mechanism to bootstrap a demo gravity flip region when regions.json is absent or empty.
- The showcase region features a 10×20×10 box with upward force and Torch_Fire particles, allowing immediate demonstration of functionality.
- Users can customize or remove this region via regions.json.

src/main/java/com/mythlane/gravityflip/GravityFlipPlugin.java

@@ -4,11 +4,14 @@ import com.hypixel.hytale.server.core.plugin.JavaPlugin;
 import com.hypixel.hytale.server.core.plugin.JavaPluginInit;
 import com.hypixel.hytale.server.core.universe.Universe;
 import com.hypixel.hytale.server.core.universe.world.World;
+import com.hypixel.hytale.math.shape.Box;
+import com.hypixel.hytale.math.vector.Vector3d;
 import com.hypixel.hytale.server.core.util.Config;
 import com.mythlane.gravityflip.config.GravityFlipConfig;
 import com.mythlane.gravityflip.physics.FallDamageGuard;
 import com.mythlane.gravityflip.physics.FallDamageSuppressorSystem;
 import com.mythlane.gravityflip.physics.GravityApplier;
+import com.mythlane.gravityflip.region.GravityFlipRegion;
 import com.mythlane.gravityflip.region.RegionRegistry;
 import com.mythlane.gravityflip.tick.RegionTickLoop;
 import com.mythlane.gravityflip.viz.RegionVisualizer;
@@ -72,6 +75,12 @@ public class GravityFlipPlugin extends JavaPlugin {
     protected void start() {
         super.start();
         GravityFlipConfig cfg = configHolder.get();
+        if (cfg.getRegions().isEmpty()) {
+            cfg.getRegions().add(buildShowcaseRegion());
+            configHolder.save();
+            getLogger().at(Level.INFO).log(
+                    "First-run: bootstrapped 1 showcase region in regions.json (edit or delete to customise)");
+        }
         this.registry = new RegionRegistry(cfg, configHolder);
         this.gravityApplier = new GravityApplier(
                 th -> getLogger().at(Level.WARNING).withCause(th).log("gravityApply failed"),
@@ -120,6 +129,25 @@ public class GravityFlipPlugin extends JavaPlugin {
         super.shutdown();
     }
 
+    /**
+     * Showcase zone seeded on first run (when {@code regions.json} is absent or empty).
+     * 10×20×10 box at {@code (0,100,0)..(10,120,10)} with Torch_Fire particles and a
+     * gentle upward force — lets a fresh install demonstrate the feature immediately.
+     * Users are free to edit or delete this zone via {@code regions.json}.
+     */
+    private static GravityFlipRegion buildShowcaseRegion() {
+        GravityFlipRegion r = new GravityFlipRegion(
+                "demo-gravity-flip",
+                new Box(new Vector3d(0, 100, 0), new Vector3d(10, 120, 10)),
+                true);
+        r.setVerticalForce(0.3);
+        r.setVisualMode("Particles");
+        r.setVisualParticleId("Torch_Fire");
+        r.setVisualParticleDensity(0.3);
+        r.setVisualRefreshMs(300);
+        return r;
+    }
+
     /** Exposed for Phase 3 (gravity physics) and Phase 4 (commands). */
     public RegionRegistry regions() { return registry; }