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.

tests/test_rally_follow_pipeline.py

@@ -0,0 +1,11 @@
+from rally_follow import video_cmd
+
+
+def test_video_cmd_without_preview_has_no_kmssink():
+    cmd = video_cmd("/dev/rally", 1920, 1080, 30, 8, preview=None)
+    s = " ".join(cmd)
+    assert "kmssink" not in s
+    assert "tee" not in cmd
+    assert "fdsink" in cmd
+    assert "fd=8" in cmd
+    assert "device=/dev/rally" in s