refactor: drop unused VFX scaffolding, single-line English doc, reduce debug logs

- Remove unused chain/ParticleTrail and chain/VolumeCurve (dead since the EntityEffect
  pivot replaced the per-particle emit path) plus their test suites.
- Drop Vec3.lerp (only consumer was ParticleTrail).
- Strip step-by-step "[N/9]" debug logs from the orchestrator and per-entity logs
  from HytaleEntitySource / HytalePlayerRayCaster / ChainDamageApplier; keep one
  summary log per click and warnings on failure.
- Extract resolveChain and tryEmitVfx helpers in ChainLightningSceptreInteraction
  so firstRun reads top-down (cooldown gate -> resolve -> damage -> vfx -> deduct).
- Translate every Java doc/comment to single-line English.

Tests: 30/30 green (29 baseline kept + 1 chain damage adapter test).
Build: ./gradlew shadowJar clean.

src/main/java/com/mythlane/chainlightning/sceptre/HytaleEntitySource.java

@@ -12,21 +12,10 @@ import com.mythlane.chainlightning.chain.Vec3;
 import javax.annotation.Nonnull;
 import java.util.ArrayList;
 import java.util.List;
-import java.util.logging.Logger;
 
-/**
- * Implementation Phase 3 de {@link EntitySource} qui delegue a
- * {@link TargetUtil#getAllEntitiesInSphere}.
- *
- * <p><b>Note importante :</b> {@code getAllEntitiesInSphere} retourne une liste THREAD-LOCALE
- * (SpatialResource.getThreadLocalReferenceList). On la consomme immediatement en mappant chaque
- * ref vers un {@link HytaleEntityAdapter} dans une nouvelle ArrayList -- la liste retournee est
- * sure a conserver entre frames.
- */
+/** Phase 3 EntitySource that copies TargetUtil's thread-local result into a stable list of snapshots. */
 public final class HytaleEntitySource implements EntitySource {
 
-    private static final Logger LOGGER = Logger.getLogger(HytaleEntitySource.class.getName());
-
     private final ComponentAccessor<EntityStore> accessor;
 
     public HytaleEntitySource(@Nonnull ComponentAccessor<EntityStore> accessor) {
@@ -36,21 +25,14 @@ public final class HytaleEntitySource implements EntitySource {
     @Override
     public List<ChainEntity> nearby(Vec3 origin, double radius) {
         Vector3d hytaleOrigin = new Vector3d(origin.x(), origin.y(), origin.z());
-        LOGGER.info(String.format("[ChainLightning][EntitySource] getAllEntitiesInSphere(origin=%s, radius=%.1f)",
-                origin, radius));
         List<Ref<EntityStore>> refs = TargetUtil.getAllEntitiesInSphere(hytaleOrigin, radius, accessor);
-        LOGGER.info(String.format("[ChainLightning][EntitySource] Hytale returned %d refs", refs == null ? -1 : refs.size()));
-        if (refs == null) {
-            return new ArrayList<>();
+        if (refs == null || refs.isEmpty()) {
+            return List.of();
         }
         List<ChainEntity> snapshots = new ArrayList<>(refs.size());
         for (Ref<EntityStore> ref : refs) {
-            ChainEntity adapter = HytaleEntityAdapter.snapshot(ref, accessor);
-            LOGGER.info(String.format("[ChainLightning][EntitySource]   ref:%d -> id=%s pos=%s alive=%s",
-                    ref.getIndex(), adapter.id(), adapter.position(), adapter.isAlive()));
-            snapshots.add(adapter);
+            snapshots.add(HytaleEntityAdapter.snapshot(ref, accessor));
         }
-        LOGGER.info(String.format("[ChainLightning][EntitySource] returning %d snapshots", snapshots.size()));
         return snapshots;
     }
 }