feat(03-01): wire GravityApplier into RegionTickLoop + plugin (Task 2)

- RegionTickLoop gagne un constructeur 3-args (registry, gravityApplier, errorHandler)
- Ancien constructeur 2-args conservé pour rétrocompat des tests Phase 02
- Tick body appelle gravityApplier.apply(w, registry.currentSnapshot(w)) après refreshFor
- GravityFlipPlugin.start() construit l'applier et l'injecte dans le tickLoop
- Log de démarrage mis à jour: 'gravity inversion active'

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

@@ -6,6 +6,7 @@ import com.hypixel.hytale.server.core.universe.Universe;
 import com.hypixel.hytale.server.core.universe.world.World;
 import com.hypixel.hytale.server.core.util.Config;
 import com.mythlane.gravityflip.config.GravityFlipConfig;
+import com.mythlane.gravityflip.physics.GravityApplier;
 import com.mythlane.gravityflip.region.RegionRegistry;
 import com.mythlane.gravityflip.tick.RegionTickLoop;
 
@@ -36,6 +37,7 @@ public class GravityFlipPlugin extends JavaPlugin {
 
     private RegionRegistry registry;
     private RegionTickLoop tickLoop;
+    private GravityApplier gravityApplier;
 
     public GravityFlipPlugin(JavaPluginInit init) {
         super(init);
@@ -61,7 +63,9 @@ public class GravityFlipPlugin extends JavaPlugin {
         super.start();
         GravityFlipConfig cfg = configHolder.get();
         this.registry = new RegionRegistry(cfg, configHolder);
-        this.tickLoop = new RegionTickLoop(registry, th ->
+        this.gravityApplier = new GravityApplier(th ->
+                getLogger().at(Level.WARNING).withCause(th).log("gravityApply failed"));
+        this.tickLoop = new RegionTickLoop(registry, gravityApplier, th ->
                 getLogger().at(Level.WARNING).withCause(th).log("detectTick failed"));
 
         // Lazy world resolution — see setup() comment.
@@ -81,7 +85,7 @@ public class GravityFlipPlugin extends JavaPlugin {
         } catch (Throwable ignored) { /* manual shutdown() fallback */ }
 
         getLogger().at(Level.INFO).log(
-                "Gravity Flip enabled — %d region(s) loaded, detector @100ms",
+                "Gravity Flip enabled — %d region(s) loaded, detector @100ms, gravity inversion active",
                 cfg.getRegions().size());
     }
 

src/main/java/com/mythlane/gravityflip/tick/RegionTickLoop.java

@@ -1,6 +1,7 @@
 package com.mythlane.gravityflip.tick;
 
 import com.hypixel.hytale.server.core.universe.world.World;
+import com.mythlane.gravityflip.physics.GravityApplier;
 import com.mythlane.gravityflip.region.RegionRegistry;
 
 import java.util.concurrent.Executors;
@@ -32,9 +33,15 @@ public final class RegionTickLoop {
     private volatile ScheduledFuture<?> future;
     private final Consumer<Throwable> errorHandler;
     private final RegionRegistry registry;
+    private final GravityApplier gravityApplier;
 
     public RegionTickLoop(RegionRegistry registry, Consumer<Throwable> errorHandler) {
+        this(registry, null, errorHandler);
+    }
+
+    public RegionTickLoop(RegionRegistry registry, GravityApplier gravityApplier, Consumer<Throwable> errorHandler) {
         this.registry = registry;
+        this.gravityApplier = gravityApplier;
         this.errorHandler = errorHandler == null ? t -> {} : errorHandler;
         this.scheduler = Executors.newSingleThreadScheduledExecutor(r -> {
             Thread t = new Thread(r, "GravityFlip-Detect");
@@ -65,6 +72,9 @@ public final class RegionTickLoop {
             World w = worldSupplier.get();
             if (w == null) return;
             registry.refreshFor(w);
+            if (gravityApplier != null) {
+                gravityApplier.apply(w, registry.currentSnapshot(w));
+            }
         };
         scheduleGuarded(initialDelayMs, tick);
     }