Fix ledge transitions and root motion loops (#91)

## Summary

- resolve each ledge action to the walkable segment on the stage-interior side
- preserve repeating root-motion displacement across every animation cycle
- add regression coverage for left/right ledge segments and multiple root-motion wraps
- Implement ledge intangibility

Reviewed-on: #91
Co-authored-by: Álex Román Núñez <eirexe@eirteam.moe>

src/fighter/baked_animation/runtime.rs

@@ -110,6 +110,9 @@ impl BakedFighterAnimations {
             .get(&kind)
             .and_then(|index| self.clips.get(*index))
     }
+    pub fn get_animation_duration(&self, kind: AnimKind) -> Option<usize> {
+        self.clip(kind).map(|clip| clip.frames.len())
+    }
 }
 
 #[derive(Component, Clone, Debug, Default, Hash)]
@@ -411,7 +414,9 @@ impl FighterBoneMatrices {
                     previous.kind == animation_frame.kind
                         && previous.frame.saturating_add(1) == animation_frame.frame
                 })
-                && root_motion_loop_frame_count == Some(animation_frame.frame)
+                && root_motion_loop_frame_count.is_some_and(|loop_frame_count| {
+                    loop_frame_count > 0 && animation_frame.frame % loop_frame_count == 0
+                })
             {
                 delta = delta + root_motion_cycle_delta;
             }