Download a screen's firmware and put it on from your own computer (0.2.68)

GitHub issue #8: Home Assistant on a server or virtual machine is out of
reach of the screen. New screen and Firmware & USB get a Download choice:
ESP Screens builds the profile's firmware as always and offers ESPHome's
factory image, which the owner flashes with ESPHome Web in Chrome or Edge.

- Firmware: a download job compiles without uploading; only the image of
  the profile's latest successful build in this process is served, a new
  job withdraws it, and a build without a factory image fails.
- USB on the Home Assistant machine stays first in both lists, also before
  a board is plugged in; Download and Later stay chosen once picked.
- The not-yet-in-Home-Assistant card knows a downloaded screen.
- The device name pattern is valid again under Chrome's v flag.
- Docs: README, DOCS, EASY_SETUP, DOCKER, TROUBLESHOOTING. App only;
  firmware stays 0.2.58.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

docs/DOCKER.md

@@ -75,6 +75,9 @@ under **Settings → Devices & services** in Home Assistant, and then choose the
 - **USB (Linux only):** connect the screen, uncomment `devices:` in `compose.yaml` with its
   port (`/dev/ttyUSB0` or `/dev/ttyACM0`), and run `docker compose up -d` again. Installs
   over Wi-Fi (OTA) and the nightly updates need nothing extra.
+- **Without USB passthrough (app 0.2.68+):** in **New screen**, choose **Download · flash from
+  your own computer**. The container builds the firmware, and you put it on the screen with
+  [ESPHome Web](https://web.esphome.io) in Chrome or Edge on the computer the screen is plugged into.
 - **Backups:** Home Assistant backups don't include this container. Keep a copy of
   `data/screens.json` and `data/updates.json` (layouts and update settings) and of the
   ESPHome folder. `data/build` and `data/platformio` are caches.