Files stored as {files_path}/{id} (no extension). The ext parameter
is removed from Save/Read/Delete in both the port interface and
the implementation.
Thumbnail and Preview both use imaging.Thumbnail (fit within
configured max bounds, never upscale, never crop) — the config
values THUMB_WIDTH/HEIGHT and PREVIEW_WIDTH/HEIGHT are upper limits,
not forced dimensions.
Non-decodable files (video, etc.) receive a #444455 placeholder.
Cache writes use atomic temp→rename; on cache failure the generated
image is served from memory so the request still succeeds.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Masahiko AMANO
fae87ad05c