refactor: clean GSD comments and translate remaining Java sources to English

- Reduce javadocs to one-liners across config/region/physics/tick/viz/plugin root

- Translate residual French comments; no behavioural change

- Tests adjusted where assertions referenced French strings

src/test/java/com/mythlane/gravityflip/physics/FallDamageGuardTest.java

@@ -10,10 +10,7 @@ import java.util.UUID;
 import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
-/**
- * Pure-data tests for {@link FallDamageGuard} — no Hytale runtime dependency.
- * Covers entry / in-region / exit / grace-window / re-entry / FallDamage=true override.
- */
+/** Pure-data tests for {@link FallDamageGuard} — entry, in-region, exit, grace-window, re-entry. */
 class FallDamageGuardTest {
 
     @Test
@@ -69,8 +66,7 @@ class FallDamageGuardTest {
         GravityFlipRegion region = region(false, 2500);
         guard.markInRegion(uuid, region);
         guard.markExit(uuid, region, 1000L);
-        guard.markInRegion(uuid, region);  // re-enter
-        // In-region again with FallDamage=false → immediate suppression, grace reset.
+        guard.markInRegion(uuid, region);
         assertTrue(guard.shouldSuppressFallDamage(uuid, 1500L));
     }
 
@@ -82,7 +78,6 @@ class FallDamageGuardTest {
         GravityFlipRegion allowed = region(true, 2500);
         guard.markInRegion(uuid, suppressed);
         guard.markExit(uuid, suppressed, 1000L);
-        // New region has FallDamage=true → override immediately.
         guard.markInRegion(uuid, allowed);
         assertFalse(guard.shouldSuppressFallDamage(uuid, 1500L));
     }

src/test/java/com/mythlane/gravityflip/physics/GravityApplierDiffTest.java

@@ -8,14 +8,7 @@ import java.util.UUID;
 
 import static org.junit.jupiter.api.Assertions.*;
 
-/**
- * Pure-diff + tracker-semantics tests for {@link GravityApplier}.
- *
- * <p>Pas de mocks (pattern Phase 02-02 deviation #4). Pas de runtime Hytale requis —
- * les tests 5 et 6 utilisent le hook package-private {@code __updateTrackerForTest} et
- * la vue {@code previouslyInvertedView()} pour valider la sémantique du tracker sans
- * toucher à {@code World} / {@code Store}.
- */
+/** Pure-diff + tracker-semantics tests for {@link GravityApplier}. */
 class GravityApplierDiffTest {
 
     @Test
@@ -73,16 +66,12 @@ class GravityApplierDiffTest {
         applier.__updateTrackerForTest(new HashSet<>(Set.of(c)));
         assertEquals(Set.of(c), applier.previouslyInvertedView());
 
-        // View is immutable.
         Set<UUID> view = applier.previouslyInvertedView();
         assertThrows(UnsupportedOperationException.class, () -> view.add(UUID.randomUUID()));
     }
 
-    // NOTE (Rule 3 deviation — Plan 03-02) : les tests suivants ciblent la seam pure
-    // `buildFlaggedDecision(double, double, boolean)` au lieu de `buildPhysicsValuesWithFlag`
-    // parce que le static init de `PhysicsValues` déclenche un `ExceptionInInitializerError`
-    // hors runtime Hytale (dépendance ModuleRegistry). La décomposition pure garantit la
-    // sémantique attendue (mass/drag préservés, flag = target) sans couplage ECS.
+    // These tests target the pure seam buildFlaggedDecision because PhysicsValues static init
+    // triggers ExceptionInInitializerError outside the Hytale runtime.
 
     @Test
     void buildFlaggedDecisionPreservesMassAndDrag() {