Adds a parallel ThumbHash placeholder everywhere BlurHash is already used.
Remote events now carry both hashes; renderers prefer thumbhash when
available and fall back to blurhash. The MIP-04 `thumbhash` imeta field
that was previously reserved-but-unused is now wired end-to-end.
- New ThumbHash encoder/decoder in commons/commonMain (no new Gradle dep)
- New ThumbhashTag and thumbhash accessors/builders across NIP-17, 68,
71, 94, 95, 99, the experimental profile gallery, and MIP-04
- RichTextParser + MediaContentModels carry a thumbhash field alongside
blurhash so every downstream composable can pick its preferred placeholder
- New ThumbHashFetcher (Android + Desktop) registered with Coil, plus a
small placeholderModel(thumbhash, blurhash) helper centralising the
"prefer thumbhash, fall back to blurhash" rule
- Rename BlurhashMetadataCalculator -> PreviewMetadataCalculator; the
calculator decodes the bitmap / video thumbnail once and runs both
encoders on the same pixels to keep upload cost flat
- DesktopMediaMetadata, MediaUploadResult, and FileHeader now surface
both hashes through the NIP-96, Blossom, NIP-95, MIP-04, NIP-17 DM,
Classifieds, picture, video, and long-form upload paths
- Round-trip unit test for the ThumbHash port
Claude
b2f297b3bb