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_i420_nv12.py

@@ -0,0 +1,56 @@
+from i420_nv12 import (
+    coded_dim,
+    drop_va_pad_i420,
+    i420_to_nv12_into,
+    nv12_bytes,
+    va_visible_height,
+)
+
+def test_coded_dim_pads_up():
+    assert coded_dim(360) == 368
+    assert coded_dim(1080) == 1088
+    assert coded_dim(640) == 640
+    assert coded_dim(352) == 352
+
+
+def test_i420_to_nv12_pads_last_row():
+    w, h = 640, 360
+    ysz = w * h
+    uv = (w // 2) * (h // 2)
+    src = bytearray(ysz + 2 * uv)
+    src[:ysz] = b"\x80" * ysz
+    src[(h - 1) * w:ysz] = b"\x90" * w
+    src[ysz:ysz + uv] = b"\x40" * uv
+    src[ysz + uv:] = b"\xc0" * uv
+    cw, ch = 640, 368
+    out = bytearray(nv12_bytes(cw, ch))
+    n = i420_to_nv12_into(src, w, h, out)
+    assert n == nv12_bytes(cw, ch)
+    assert out[0] == 0x80
+    # cloned pad rows 360-367
+    assert out[360 * cw] == 0x90
+    assert out[367 * cw] == 0x90
+    assert out[cw * ch] == 0x40
+    assert out[cw * ch + 1] == 0xc0
+
+
+def test_drop_va_pad_restores_360():
+    w, h = 640, 368
+    vis = 360
+    ysz = w * h
+    uv = (w // 2) * (h // 2)
+    src = bytearray(ysz + 2 * uv)
+    src[: w * vis] = b"\x77" * (w * vis)
+    src[w * vis:ysz] = b"\x11" * (w * 8)
+    out, ow, oh = drop_va_pad_i420(src, w, h)
+    assert (ow, oh) == (w, vis)
+    assert len(out) == w * vis * 3 // 2
+    assert out[0] == 0x77
+    assert 0x11 not in out[: w * vis]
+
+
+def test_va_visible_height():
+    assert va_visible_height(640, 368) == 360
+    assert va_visible_height(1920, 1088) == 1080
+    assert va_visible_height(640, 360) == 360
+    assert va_visible_height(640, 352) == 352