chore: Arc B580 offload spike script

Read-only probe: CUDA unusable, OpenCL sees the B580, OpenVINO not
installed. Per-worker GPU still out of scope.

README.md

@@ -69,6 +69,32 @@ re-run `--write` unless you intend to remap slots.
 .venv/bin/python run.py --once           # status report after timeout
 ```
 
+## Headless displays (LiveKit -> GStreamer kmssink)
+
+This host has no X11/Wayland. `run_displays.py` joins the LiveKit room as
+`display-wall` (subscribe-only) and pipes each camera's video into a
+GStreamer `kmssink` on a DRM connector.
+
+Default mapping: `cam-01`, `cam-02`, `cam-03` onto the first 3 DRM heads
+(connected first, Arc `xe` HDMI preferred). Today HDMI-A-7 is the live 4K
+panel; plug two more HDMI cables into the Arc card (`HDMI-A-5`/`HDMI-A-6`)
+and they light up on the same process.
+
+```bash
+.venv/bin/python run_displays.py --list
+.venv/bin/python run_displays.py --test-pattern   # smpte/ball/snow, no LiveKit
+.venv/bin/python run_displays.py                  # subscribe cam-01..03
+.venv/bin/python run_displays.py --connectors HDMI-A-7,HDMI-A-6,HDMI-A-5
+
+sudo cp deploy/livekit-displays.service /etc/systemd/system/
+sudo systemctl daemon-reload
+sudo systemctl enable --now livekit-displays
+```
+
+`DISPLAY_IDENTITIES` / `DISPLAY_CONNECTORS` / `DISPLAY_COUNT` in `.env`.
+kmssink takes the DRM master for those connectors (the framebuffer console
+on HDMI-A-7 will be replaced by camera video).
+
 ## Audio cleanup
 
 C920 mics are 16 kHz **stereo**. Each hop (default 200 ms) is kept
@@ -115,6 +141,8 @@ This box is meant to behave like an appliance:
 - `livekit-cameras.service` — publishers. `Wants=` the test server, does not
   `Require` it. Destination is `LIVEKIT_URL` in `.env` (currently
   `ws://127.0.0.1:7880`).
+- `livekit-displays.service` — optional. Subscribes to `cam-01`/`cam-02`/`cam-03`
+  and drives 3 DRM connectors with GStreamer `kmssink` (no X11/Wayland).
 
 When the real/remote LiveKit exists, change `.env` `LIVEKIT_URL` and: