feat(p0-3): Uni3C ControlNet support for Wan2.1 video pipeline (#8)

- Add ControlNetType enum (13 types: depth/canny/pose/hed/normal/segment/lineart/shuffle/mlsd/softedge/openpose/recolor/ip2p)
- Add Uni3CConfig dataclass with auto preprocessor mapping and serialization
- Add generate_video_wan_controlnet() to wan_video.py with DashScope control_image support
- Add _build_controlnet_prompt() helper for control-type-specific prompt engineering
- Add list_controlnet_types() registry with recommended_use metadata
- Update video_router.py with ControlNet routing (generate_controlnet_video, task registration)
- Add 35 comprehensive tests covering enum/config/prompt/routing/validation
- Full suite: 48/48 tests pass, 0 regressions

Co-authored-by: JKLLLLLLL <31589087+LLLLLive@users.noreply.github.com>

Author: jklthinking