c836ac604d
Handle character-action generation results as real video assets: use backend previewVideoPath as layer src, set mediaType="video" and assetKind="character-animation", and store the first frame only as thumbnail/poster. Update docs to document the new behavior and preserve backend frame extraction/green-screen workflows. Update UI/UX: compact parameter labels (e.g. "16:9·1K"), quick-edit treats original image as an implicit last reference (hidden from the reference bar) and allows editable bottom capsules, and ensure exports preserve true media file types. Change upload toolbar icon to Upload and add tests to cover the icon and video-layer behavior; also add serialization/hydration test for video thumbnails and adjust many integration/unit tests to reflect new labels, sizes and generation semantics. Files touched include multiple docs under docs/, edited components and tests under src/components/image-editor/, and minor stylesheet updates.