Move reusable GUI primitives (PanelTile, EditablePanelTile, base Tile,
ElevatedPill, SingleLineTextEdit) into the shared dashgui package and
consume them via a file: dependency. EditablePanelTile now accepts an
onError prop so error notification stays app-side.
- Add category image API methods (upload/delete) to src/api/index.js
- Add uploadCategoryImage/deleteCategoryImage thunks and extraReducers in categorySlice
- Add CategoryBackdrop component showing ThumbHash placeholder with full thumb overlay
- Add photo upload/delete tab to CategoryEditTile settings cycle
- Category tile label band uses semi-transparent black overlay with white text
- Pass thumbHash/fullHash to both CategoryTile and CategoryEditTile
After toggling a POS category, update the category's posterminalIds array
in-place rather than re-fetching the entire tree. This keeps the settings
cycle open on the same terminal. Also fix off-by-one in terminal cycling
and ensure posterminals load on category page mount.
