Add READMEs, docs, and LICENSE for publishing

- LICENSE: MIT, with attribution notes for the vendored qrcode/epaper_fonts/
  dns_server code and the epd7in3e driver's transcription of Waveshare's
  register sequence.
- Top-level README.md: project overview, hardware list, quick-start
  pointing at firmware/ and server/, repo layout, license, Claude Code
  attribution.
- firmware/README.md: full rewrite (was still the stock ESP-IDF captive
  portal example's README) -- build/flash instructions, Kconfig reference
  table, first-boot walkthrough, and how to reset to provisioning mode via
  NVS erase (the only way in right now; a proper reconfigure trigger is a
  future addition).
- docs/hardware.md: wiring table + parts list + strapping-pin/SPI-speed notes.
- docs/architecture.md: sequence diagram and walkthrough of the full
  provision -> connect -> fetch -> display -> sleep cycle, plus the
  reasoning behind doing image processing server-side and reusing Immich's
  face detection instead of bundling a detector.
- server/README.md: fixed stale endpoint docs (missing GET /frame/config,
  POST /api/config still describing removed immich_url/api_key fields).

README.md

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+# ESPresso Frame
+
+A DIY e-ink photo frame: an ESP32-C6 pulls photos from your
+[Immich](https://immich.app) library and displays them on a 7.3" full-color
+e-paper panel, waking on a timer to refresh and spending the rest of its
+time in deep sleep.
+
+- **No cables to a computer, no SD card shuffling.** Provisioning is a
+  captive portal with a QR code drawn on the panel itself -- scan, join,
+  fill in your WiFi and server address, done.
+- **The frame never decodes an image.** A small self-hosted server does
+  all the work (pulling from Immich, cropping, dithering, packing into
+  the panel's exact pixel format) and hands the device a stream it can
+  write straight to SPI. The ESP32-C6 has no PSRAM and not much SRAM to
+  spare -- keeping it a dumb display client is what makes that workable.
+- **Crops toward faces, not just the center**, using face bounding boxes
+  Immich already computed for its own People feature -- no bundled face
+  detector.
+- **Refresh interval and album are configurable from a web UI**, no
+  reflashing needed to change them.
+
+## Hardware
+
+- ESP32-C6 dev board (8MB flash)
+- [Waveshare 7.3" E Ink Spectra 6 (E6)](https://www.waveshare.com/7.3inch-e-paper-hat-e.htm) panel -- 800x480, 6-color, SPI
+
+See [`docs/hardware.md`](docs/hardware.md) for wiring and
+[`docs/architecture.md`](docs/architecture.md) for how the two halves talk
+to each other.
+
+## Getting started
+
+1. **[`server/`](server/)** -- run the FastAPI server first (Docker
+   Compose, points at your Immich instance). See
+   [`server/README.md`](server/README.md).
+2. **[`firmware/`](firmware/)** -- build and flash the ESP32-C6, then
+   scan the QR codes it draws on first boot to provision it. See
+   [`firmware/README.md`](firmware/README.md).
+
+## Repo layout
+
+```
+firmware/   ESP-IDF project for the ESP32-C6
+server/     FastAPI server: Immich -> crop/dither/pack -> the frame
+docs/       Wiring and architecture notes
+```
+
+## License
+
+MIT -- see [`LICENSE`](LICENSE). A few small pieces of vendored
+third-party code (a QR code generator, a bitmap font table) keep their
+own permissive licenses; see `LICENSE` for details.
+
+---
+
+Built with substantial assistance from [Claude Code](https://claude.com/claude-code).