feat(modes): A2V + Lipsync + Keyframe + Style parameterize_fn

feat(modes): T2V + I2V parameterize_fn with stage maps

feat(modes): Mode dataclass + empty MODE_REGISTRY skeleton

feat(workflow): set_input + validate over node graph

feat(workflow): load_template returns fresh deep copy per mode

feat(tools): extract six mode templates from master workflow JSON

test: pytest fixtures (master_workflow, canonical_inputs, fake_hf_cache)