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.

h264_fifo.py

@@ -0,0 +1,29 @@
+"""Named-pipe helpers for the capture <-> display H.264 sidecar.
+
+Linux fifos deadlock if one side opens O_RDONLY and the other O_WRONLY
+before either has a partner. Opening O_RDWR in the parent first makes
+filesink/filesrc open() return immediately.
+"""
+from __future__ import annotations
+
+import os
+import stat
+
+
+def hold_fifo(path: str, mode: int = 0o644) -> int:
+    """Create `path` as a fifo if needed and open it O_RDWR | O_NONBLOCK.
+
+    Do not unlink an existing fifo: that splits the inode from any process
+    already blocked in open() and recreates the deadlock.
+    """
+    directory = os.path.dirname(path)
+    if directory:
+        os.makedirs(directory, exist_ok=True)
+    try:
+        st = os.stat(path)
+        if not stat.S_ISFIFO(st.st_mode):
+            os.unlink(path)
+            os.mkfifo(path, mode)
+    except FileNotFoundError:
+        os.mkfifo(path, mode)
+    return os.open(path, os.O_RDWR | os.O_NONBLOCK)