Function walkStairs

walkStairs(
    world: World,
    character: KCC,
    deltaTime: number,
    stepUp: Vec3,
    stepForward: Vec3,
    stepForwardTest: Vec3,
    stepDownExtra: Vec3,
    filter: filter.Filter,
    listener: CharacterListener | undefined,
): boolean
Attempts to walk up stairs.
1. Sweep up to find headroom
2. Collect steep slope normals we're pushing against
3. Move horizontally at elevated position
4. Check that we made progress toward steep slopes
5. Sweep down to find floor
6. Validate floor is not too steep (or use forward test)
7. Move to final position
8. Override ground state to ON_GROUND
Parameters
- world: World
  the physics world
- character: KCC
  the character controller
- deltaTime: number
  time step
- stepUp: Vec3
  up step vector (e.g., [0, 0.4, 0])
- stepForward: Vec3
  forward step vector (based on velocity * deltaTime)
- stepForwardTest: Vec3
  test distance for floor validation
- stepDownExtra: Vec3
  extra down step after stair walk
- filter: filter.Filter
  collision filter
- listener: CharacterListener | undefined
  optional listener for callbacks
Returns boolean
true if stair walk succeeded, false otherwise
- Defined in src/character/kcc.ts:3542