5e7c47e2eb571298d5b8c6a6c28127dd500ab16a
Implements the server side of the architecture decided on: the ESP32-C6 has no PSRAM and a tight RAM budget, so all the heavy lifting (JPEG decode, resize, Floyd-Steinberg dithering, 6-color quantization, 4bpp packing) happens here instead of on-device. The frame just does a single GET and streams the response straight to SPI. - GET /frame/image: looks up the current cursor's asset in the configured Immich album, downloads its preview thumbnail, and returns it packed into the panel's exact 800x480/4bpp/2px-per-byte format (application/octet-stream, always exactly 192,000 bytes). - GET / + POST /api/config + GET /api/albums: a small web UI for entering the Immich URL/API key and picking an album, rather than cramming that into the ESP32's captive portal form. - Config (Immich creds, selected album, cursor) persists to a JSON file via a docker-compose volume mount. Verified locally with a venv (Docker isn't available in this environment): unit-tested image_pipeline against a synthetic image (exact byte count, valid panel color codes only), and ran a full end-to-end pass against a mock Immich HTTP server exercising the real /frame/image path. Pinned dependency versions in requirements.txt after hitting a real bug with unpinned floors: the latest starlette (1.3.1) resolved by `pip install fastapi` breaks Jinja2Templates outright. Not yet wired to the ESP32 side (task 6) or authenticated -- /frame/image is unauthenticated for now, fine on a trusted LAN but worth revisiting once the firmware sends a shared device token.