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/air.rs

@@ -123,6 +123,7 @@ pub fn collision_interrupt(
     ctx.ecb.left -= diff;
     ctx.ecb.right -= diff;
     ctx.translation.0 = res.hit_position;
+    ctx.presentation_snap.0 = true;
     ctx.surface.land(res.line_id);
     Some(FighterState::Land(LandingState::create(landing_type)))
 }

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,
         };
 

src/fighter/state/mod.rs

@@ -20,6 +20,7 @@ use crate::fighter::{
     Fighter, FighterECB, FighterFacingDirection, FighterHitboxes, FighterHitstop,
     FighterHitstopShake, FighterHitstopShakeKind, FighterHitstopShakeRole,
     FighterPreviousTranslation, FighterSurfaceState, FighterTranslation, FighterVelocity,
+    FighterPresentationSnap,
 };
 use crate::fighter::surface::EcbLockPolicy;
 use crate::game_settings::GameSettings;
@@ -200,6 +201,7 @@ pub struct CollisionContext<'a> {
     pub prev_ecb: &'a FighterPreviousECB,
     pub stage_collision: &'a StageCollision,
     pub leave_ground_ecb_lock_duration: u32,
+    pub presentation_snap: &'a mut FighterPresentationSnap,
     pub downward_stick_threshold: FGi32,
 }
 
@@ -244,6 +246,7 @@ fighter_states! {
 pub struct FighterFrameQuery {
     pub translation: &'static mut FighterTranslation,
     pub prev_translation: &'static mut FighterPreviousTranslation,
+    pub presentation_snap: &'static mut FighterPresentationSnap,
     pub input: &'static mut FighterInput,
     pub hitboxes: &'static mut FighterHitboxes,
     pub velocity: &'static mut FighterVelocity,
@@ -354,6 +357,7 @@ impl<'w, 's> FighterFrameQueryItem<'w, 's> {
         CollisionContext {
             translation: &mut self.translation,
             prev_translation: &self.prev_translation,
+            presentation_snap: &mut self.presentation_snap,
             input: &self.input,
             velocity: &mut self.velocity,
             surface: &mut self.surface,