9c7b3ad16d
Adds Seedance 2.0 reference-media constraints and forbids video data URLs; updates docs/decision-log and pitfalls to record the new rules. Introduces typed audio params (type: one-shot|loop, tempo: number|null), generator-specific placeholder styles/avoidance and UI changes for generation panels. Implements related front-end changes (new crop/ raster edit components, many image-editor models, tests and workflow hooks) and server-side contract/handler updates across api-server, shared-contracts, platform-audio, platform-image and vector_engine_audio_generation to support the new submission/asset flow and validations.