radio: stop a dead PulseAudio from crash-looping the whole radio

Field report: the radio died and kept restarting. The log chain is
unambiguous - "Daemon startup failed" (pulse), then Connection refused on
input.pulseaudio_0 / buffer.consumer_0 / pulse_out, then "Shutdown
started!", then round again.

Three fixes:

* Clear stale pulse runtime state before starting the daemon. /run is part
  of the container's writable layer, so "docker restart" - and the loop that
  restart:unless-stopped produces - preserves /run/pulse/pid from the killed
  daemon; the next start then refuses with "Daemon startup failed", which is
  what makes the loop self-sustaining. We only remove it when no pulseaudio
  process is actually alive.

* When pulse still won't start, say so loudly and explain the consequence
  and the way out (Icecast needs no sound device; comment the pulse tor out),
  instead of a one-line WARNING that gets lost above the traceback.

* output.pulseaudio(fallible=true): the local monitor output can now fail
  without failing its clock and tearing down the radio. The mic input stays
  a hard dependency - documented inline, since removing it changes audio
  behaviour and cannot be verified without a liquidsoap runtime.

Also: RADIO_FORCE_SCRIPT=1 re-seeds radio_conjurer.liq from the image
(keeping a .bak). The live script is deliberately never overwritten so hand
edits win - but that also means image fixes never reached volumes seeded
long ago, which is why a running radio can still hold a stale script.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

conjurer_musician/radio_conjurer.liq

@@ -155,7 +155,13 @@ interactive.persistent("/srv/betoniarka/data/script.params")
 # Configure output formats and destinations
 
 output.icecast(%mp3, host="localhost", port=8000, password=credentials.password, icy_metadata="true", mount="mp3-stream", radio)
-output.pulseaudio(radio)
+# Local monitor output. fallible=true so a dead or missing pulse daemon degrades
+# to "no monitor" instead of failing its clock and taking the whole radio down
+# with it ("Shutdown started!"). The stream that actually matters is the Icecast
+# one above, which needs no sound device at all.
+# NOTE: input.pulseaudio() (the mic, further up) is still a HARD dependency - on
+# a headless container with no capture device, comment BOTH of them out.
+output.pulseaudio(fallible=true, radio)
 #output.file.hls("/tmp/hls", [("mp3-low", %mp3(bitrate=96)), ("mp3-hi", %mp3(bitrate=160))], radio)
 # Uncomment the following lines to enable additional output formats
 # output.icecast(%opus, host="retropie", port=8000, password=credentials.password, icy_metadata="true", mount="opus-stream", radio)