Replace stringly-typed entity references with a compile-time-safe
EntityType enum throughout timeline events, images, and repository
operations. Also replace raw i64 fields in TimelineBrewData with
typed BagId/GearId wrappers.
Add ImageData newtype that wraps Option<String> with a custom Debug impl
showing Some(<image>)/None instead of raw base64. Replace image fields on
all 14 submission structs and remove payload from tracing skip lists so
textual/numeric fields appear in spans.
Add image infrastructure, API, and detail page integration:
- EntityImage domain model with ImageRepository trait
- SQLite storage for images and thumbnails as BLOBs
- Image processing with data URL decoding and thumbnail generation
- REST API: upload, get, delete, thumbnail at /{entity_type}/{id}/image
- resolve_image_url helper for image fallback chains
- image-upload web component for direct upload on detail pages
- Image display with vignette overlay and lightbox viewer
- Template macros: image_thumbnail, readonly_image, lightbox_script
- All 7 detail pages updated with image thumbnails
- Brew images fall back to roast; cup images fall back to cafe then roast
- Delete handler macro extended with optional image cleanup
