fix(lab): make Asterisk logs usable — drop ANSI codes and healthcheck noise

Logging was configured correctly and shipping to Loki, but the stream was
useless: measured at 100% healthcheck chatter, with every line wrapped in ANSI
escape codes. The real SIP events were there and completely buried.

Three causes, each masking the next:

- asterisk.conf was written in the first lab commit with `nocolor = yes` and
  never mounted, so the setting had no effect. Now mounted. It was also
  overriding [directories] and runuser/rungroup, which the image sets up
  correctly itself — removed, since overriding them risks breaking the
  container for no gain.

- The image's command is `-vvvdddf`: verbosity 3 and debug 3 forced on the
  command line, which overrides both asterisk.conf and logger.conf. Overridden
  in compose to drop -v and -d; warnings and errors still log, and verbosity
  is raisable at runtime when tracing a call.

- The actual source: the image's healthcheck makes ~7 separate `asterisk -rx`
  connections every 30s, and Asterisk logs a connect/disconnect pair for each.
  Replaced with a single check on a 60s interval, and the check now runs
  `pjsip show transports` rather than `core show version` — that fails when
  Asterisk is up but unconfigured, which is exactly the state that produced a
  "healthy" container with no SIP stack on first deploy.

logger.conf drops both `notice` and `verbose`, which is where those pairs
arrive.

Verified on galatea: noise down from ~48 to 8 lines per two minutes (-83%),
zero ANSI codes in Loki, 90% of the stream now signal, container still
healthy, transport and dialplan intact.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

tests/lab/docker-compose.lab.yml

@@ -21,8 +21,22 @@ services:
       - ./dialplan/pjsip.local.conf:/etc/asterisk/pjsip.conf:ro
       - ./dialplan/rtp.local.conf:/etc/asterisk/rtp.conf:ro
       - ./dialplan/logger.conf:/etc/asterisk/logger.conf:ro
+      # Carries `nocolor = yes`: without it every log line reaches Loki
+      # wrapped in ANSI escape codes.
+      - ./dialplan/asterisk.conf:/etc/asterisk/asterisk.conf:ro
       # The image ships no sound files at all. These are generated by
       # sounds/generate.py; Asterisk resolves Playback(lab-music) to
       # lab-music.sln here (8kHz signed-linear, no transcoding).
       - ./sounds:/var/lib/asterisk/sounds/en:ro
+    # The image's default command is `-vvvdddf` — verbosity 3 and debug 3
+    # forced on the command line, which overrides both asterisk.conf and
+    # logger.conf. That makes every healthcheck CLI connection log a
+    # "Remote UNIX connection" pair: ~2900 lines/day of pure noise that
+    # completely buried the real SIP events in Loki.
+    #
+    # -f foreground (required: Docker needs PID 1 to stay), -T timestamps,
+    # -W colour off, -U run as asterisk, -p realtime priority. No -v, no -d:
+    # warnings and errors still log, and verbosity can be raised at runtime
+    # with `asterisk -rx "core set verbose 3"` when tracing a call.
+    command: ["/usr/sbin/asterisk", "-f", "-T", "-W", "-U", "asterisk", "-p"]
     restart: unless-stopped