[Feature] Skeletal animation playback

[vmarcella]

Overview

Add the ability to play animation clips on skeletons, animating bone transforms
over time.

Current State

No response

Scope

Goals:

• Animation player component
• Play/pause/stop controls
• Playback speed control
• Loop modes
• Animation events (on loop, on finish)

Non-Goals:

• Animation blending
• Animation state machine
• Root motion

Proposed API

pub struct SkeletalAnimationClip {
  bone_tracks: HashMap<usize, AnimationTrack<Transform>>,
  duration: f32,
}

pub struct AnimationPlayer {
  clip: Handle<SkeletalAnimationClip>,
  time: f32,
  speed: f32,
  playing: bool,
  looping: bool,
}

impl AnimationPlayer {
  pub fn new(clip: Handle<SkeletalAnimationClip>) -> Self;
  pub fn play(&mut self);
  pub fn pause(&mut self);
  pub fn stop(&mut self);
  pub fn set_speed(&mut self, speed: f32);
  pub fn set_looping(&mut self, looping: bool);
  pub fn update(&mut self, dt: f32);
  pub fn apply_to_pose(&self, clip: &SkeletalAnimationClip, pose: &mut Pose);
}

Acceptance Criteria

• Animation plays at correct speed
• Bone transforms update per frame
• Looping restarts at end
• Speed multiplier works (0.5x, 2x)
• Pose reflects animation state

Affected Crates

lambda-rs

Notes

• Track per bone index, not name (for speed)
• Consider lazy pose computation