fix(lab): silence Asterisk noise at the source, keep notice logging

Follow-up to 3150f78, which over-corrected. Dropping `notice` from logger.conf
made the log quiet by making the gateway undebuggable: Asterisk reports
rejected SIP requests at notice level via log_failed_request ("No matching
endpoint found", "Failed to authenticate"), and on a box whose entire job is
answering SIP those are the most useful lines it produces. A call was refused
and nothing said so.

`notice` is restored. The noise is dealt with where it originates instead:

- modules.conf, new. The image ships `autoload=yes` and loads every module it
  was built with, including chan_alsa on a container with no sound card:
  ~74 ALSA config errors per restart, plus module-load ERRORs for CDR/CEL
  backends, LDAP/ODBC realtime config, and format_ogg_vorbis — none of which
  can work here. Explicit noload for those; autoload stays on, because an
  allow-list would break quietly the first time a scenario needs a module
  nobody remembered to add.

- The healthcheck reduction from 3150f78 (one CLI connection on a 60s
  interval, rather than the image's ~7 every 30s) does the rest.

Verified on galatea: ALSA lines 74 → 0, all startup ERRORs gone (only one-off
benign WARNINGs remain), steady-state 4 lines per 2 minutes against ~840 per
30 minutes originally — and a refused call still logs 6 diagnostic lines.
Transport bound, both endpoints and dialplan loaded, container healthy.

`verbose` stays excluded: dialplan execution is worth having when tracing a
specific call, not worth shipping to Loki continuously. Raise it at runtime
with `asterisk -rx "core set verbose 3"`.

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

tests/lab/docker-compose.lab.yml

@@ -24,6 +24,9 @@ services:
       # Carries `nocolor = yes`: without it every log line reaches Loki
       # wrapped in ANSI escape codes.
       - ./dialplan/asterisk.conf:/etc/asterisk/asterisk.conf:ro
+      # noload for hardware/DB modules this container cannot use — the image
+      # autoloads everything, which costs ~74 ALSA lines per restart.
+      - ./dialplan/modules.conf:/etc/asterisk/modules.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).