feat: the camera's own colour, a reading that keeps its place, and cloud links in Settings

- RAW opens at the colour the camera wrote into it: the develop carries the
  difference against the file's own preview (previewResidual) instead of the
  per-channel cubic fit, dE00 6.04 -> 0.54; previewMatch.ts keeps only the grid.
- Immich reading: keyset position kept across visits, one reading per node,
  a page in flight retried, timeline buckets for the years on offer.
- The wall draws a server frame at the address the proxy serves it (no blob
  minted for it), and the 80-thumbnail pre-cache on open is gone.
- Settings lists the cloud links, flags two that answer at the same address,
  and forgets one.
- Custom frames imported from a file (engine/customFrame.ts, IndexedDB).
- Upload an edited frame from Studio to Immich Cloud.

docker/frontend/shared/types/index.ts

@@ -6,7 +6,8 @@ export type FrameId =
   | 'wallframe' // WALL FRAME PORTRAIT — the artwork hung 90° CW
   | 'wallframe-landscape' // the same artwork upright: WALL FRAME LANDSCAPE
   | 'old-film' // OLD FILM LANDSCAPE — the distressed sheet as it is
-  | 'old-film-portrait'; // OLD FILM PORTRAIT — the same sheet turned 90° CW
+  | 'old-film-portrait' // OLD FILM PORTRAIT — the same sheet turned 90° CW
+  | 'custom'; // CUSTOM IMPORTED FRAME — transparent PNG/WebP overlay
 
 // Viewfinder/composition aspect-ratio selector. Convention is an UPRIGHT
 // (portrait) picture: "4:3" = standing 3:4 photo (w/h = 3/4), "3:2" = standing