feat: point the fleet at wss LiveKit room uwh-telhai

Publish and subscribe over wss://livekit.uni-wh.de:7800 and refuse
cleartext ws://. Conference room is uwh-telhai. Includes the uncommitted
encoded H.264 publish path, Rally hairpin, and KMS wall overlay.

patches/README.md

@@ -0,0 +1,15 @@
+# livekit-ffi-backpressure.patch
+
+Apply on livekit/rust-sdks (webrtc-sys VAAPI + VideoTrackSource).
+
+1. VideoSource: latest-wins pending slot — at most one OnFrame in flight;
+   a new capture overwrites pending instead of pushing another I420 onto
+   EncoderQueue.
+2. VAAPI H264 Encode: drop delta frames older than 1 frame period, or
+   Encode calls closer than 8 ms (queue drain), *before* ToI420.
+   Logs `VAAPI encode sample delay_ms=` every 90 frames so the clock
+   domain is visible in the cameras journal.
+
+Rebuild: `CC=clang CXX=clang++ cargo build --release -p livekit-ffi`
+Install: copy `target/release/liblivekit_ffi.so` to `native/` and set
+`LIVEKIT_LIB_PATH` (see systemd drop-in `ffi-backpressure.conf`).