24x7 RTMP desktop stream, client side + UAT PASS (#798)

Whole-screen KDE capture -> x264 -> RTMP, fenced to the rt slice.
Loopback mediamtx receiver; Cloudron cutover = one creds edit.
Detail: https://projects.knownelement.com/issues/798#note-4519

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NEXT.md

@@ -1,5 +1,19 @@
 # NEXT — perf-opt closeout COMPLETE (2026-08-31); #610 open-terminal fleet DONE
 
+## 2026-09-05 morning — 24x7 RTMP desktop stream, client side DONE (#798)
+- Built + UAT PASS against the LIVE desktop (logs/19-rtmp-uat.out):
+  h264+aac 1920w ~30fps, 187% of the 2-core ukrrs-rt.slice fence,
+  self-heal (kill ffmpeg -> respawn -> stream back) proven. Frames
+  captured + luma-verified. Loopback receiver ukrrs-ultix-rtmp-rx UP
+  (mediamtx 1.20.1, 127.0.0.1:1935 only).
+- HUMAN OWES (one command, installs the systemd service + creds file):
+  `cd ~/projects/ultix && ./18-rtmp-stream.sh`
+  then watch locally: `ffplay rtmp://127.0.0.1:1935/live/desktop`
+- Cloudron cutover when ready: paste ingest URL+key into
+  ~/.creds/rtmp-stream.env, `systemctl restart ukrrs-rtmp-stream`.
+- Limits + tuning record: STREAMING.md (2560w veryfast does NOT fit the
+  2-core fence until #601; x11grab GetImage caps ~20 delivered fps).
+
 ## 2026-09-05 early AM — post-update-reboot RDP outage FIXED (#611)
 - Two reboot-triggered killers: waitforx RandR race/empty-argv (shim at
   /usr/lib/x86_64-linux-gnu/xrdp/waitforx, pristine = waitforx.real) and