Fix fighter visuals after landing snap (#67)

## Summary

- Mark landing position corrections as presentation discontinuities.
- Render and frame fighters from the current position for the snap frame.
- Keep previous translation history unchanged for gameplay collision and attack logic.

Reviewed-on: #67
Co-authored-by: Álex Román Núñez <eirexe@eirteam.moe>

src/fighter/state/ground.rs

@@ -376,6 +376,7 @@ mod tests {
             right: FGVec2::lit("0.5", "0.0"),
         };
         let previous_ecb = FighterPreviousECB::from(ecb);
+        let mut presentation_snap = crate::fighter::FighterPresentationSnap::default();
         let mut context = CollisionContext {
             translation: &mut translation,
             prev_translation: &previous_translation,
@@ -386,6 +387,7 @@ mod tests {
             prev_ecb: &previous_ecb,
             stage_collision: &stage_collision,
             leave_ground_ecb_lock_duration: 10,
+            presentation_snap: &mut presentation_snap,
             downward_stick_threshold: FGi32::ONE,
         };
 
@@ -429,6 +431,7 @@ mod tests {
             right: FGVec2::lit("0.5", "0.0"),
         };
         let previous_ecb = FighterPreviousECB::from(ecb);
+        let mut presentation_snap = crate::fighter::FighterPresentationSnap::default();
         let mut context = CollisionContext {
             translation: &mut translation,
             prev_translation: &previous_translation,
@@ -439,6 +442,7 @@ mod tests {
             prev_ecb: &previous_ecb,
             stage_collision: &stage_collision,
             leave_ground_ecb_lock_duration: 10,
+            presentation_snap: &mut presentation_snap,
             downward_stick_threshold: FGi32::ONE,
         };