Deduplicate fighter state lifecycle policies (#36)

Fixes #22

Extracts shared grounded collision/friction and airborne movement/landing policies while preserving state-specific behavior. Running fighters now pass `can_walk_off = true` so they can run off platform edges. Includes grounded and airborne hitstun call sites.

Reviewed-on: #36
Co-authored-by: Álex Román Núñez <eirexe@eirteam.moe>

src/fighter/state/jump.rs

@@ -7,9 +7,7 @@ use crate::{
             CollisionContext, EnterContext, FighterState, FighterStateImpl, InterruptContext,
             UpdateContext, air,
             air_dodge::{self, AirDodgeState},
-            fall::FallState,
-            ground::{self, GroundedMotionResult, GroundedStateCommon},
-            land::{LandingState, LandingType},
+            ground::{self, GroundedStateCommon},
         },
     },
     input::FighterCommands,
@@ -84,40 +82,14 @@ impl FighterStateImpl for JumpSquatState {
 
     fn update(&mut self, state_context: &mut UpdateContext) {
         self.duration_counter += 1;
-
-        let friction =
-            if state_context.velocity.x.abs() > state_context.fighter_attributes.max_walk_vel {
-                state_context.fighter_attributes.ground_friction
-                    * state_context
-                        .game_settings
-                        .fighter_common
-                        .ground_friction_over_walk_speed_multiplier
-            } else {
-                state_context.fighter_attributes.ground_friction
-            };
-
-        let ground_velocity = state_context.velocity.x;
-
-        state_context.velocity.x += ground::apply_grounded_friction(friction, ground_velocity);
-
-        ground::apply_grounded_motion(
-            state_context.velocity,
-            state_context.translation,
-            state_context.prev_translation,
-        );
+        ground::update_friction_motion(state_context);
     }
 
     fn check_collision_interrupt(
         &mut self,
         state_context: &mut CollisionContext,
     ) -> Option<FighterState> {
-        if let GroundedMotionResult::InAir =
-            ground::collide_with_stage_grounded(state_context, &mut self.grounded_common, false)
-        {
-            Some(FighterState::Fall(FallState))
-        } else {
-            None
-        }
+        ground::collision_interrupt(state_context, &mut self.grounded_common, false)
     }
 
     fn on_enter(&mut self, state_context: &mut EnterContext) {
@@ -139,17 +111,7 @@ impl FighterStateImpl for JumpState {
     }
 
     fn update(&mut self, state_context: &mut UpdateContext) {
-        air::integrate_gravity(state_context.velocity, state_context.fighter_attributes);
-        air::apply_air_drift(
-            state_context.velocity,
-            state_context.fighter_attributes,
-            state_context.input,
-        );
-        air::apply_air_motion(
-            state_context.velocity,
-            state_context.translation,
-            state_context.prev_translation,
-        );
+        air::update_standard_motion(state_context);
     }
 
     fn on_enter(&mut self, state_context: &mut EnterContext) {
@@ -207,19 +169,10 @@ impl FighterStateImpl for JumpState {
         &mut self,
         state_context: &mut CollisionContext,
     ) -> Option<FighterState> {
-        if let Some(res) = state_context.air_collide_with_stage() {
-            // Adjust translation
-            state_context.translation.0 = res.hit_position - state_context.ecb.get_bottom_point();
-            let grounded_common = GroundedStateCommon {
-                current_line_id: res.line_id,
-            };
-            Some(FighterState::Land(LandingState::create(
-                grounded_common,
-                LandingType::Normal,
-            )))
-        } else {
-            None
-        }
+        air::collision_interrupt(
+            state_context,
+            crate::fighter::state::land::LandingType::Normal,
+        )
     }
 }