fix: quiet installer output for non-technical users; Makefile/compose cleanup

The installer dumped ~200 lines of docker layer spam, a leaked apt error,
and obsolete version warnings, alarming for non-technical users.

install.sh:
- Clean, progress-only default output; full log to /var/log/pic-install.log
- Admin password still surfaced on stdout at the end
- PIC_DEBUG=1 / --debug flag restores verbose output
- On error, prints the last 20 lines from the log file

Makefile:
- start / update / start-core compose invocations get @ prefix to suppress
  command echo, plus --quiet-pull to kill layer-download spam

docker-compose.yml + docker-compose.services.yml:
- Removed obsolete `version: '3.3'` top-level key (triggers deprecation
  warning with current Docker Compose)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

docker-compose.yml

@@ -1,5 +1,3 @@
-version: '3.3'
-
 services:
   # Reverse Proxy - Caddy for routing all .cell traffic
   caddy: