Logging framework: logfmt events in our scripts, container labels + rotated json-file logs, Caddy JSON access logs; LOGGING.md

Store-agnostic: journald + Docker logs are the only taps any collector (Alloy/Loki, VictoriaLogs, Netdata) needs.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

deploy.sh

@@ -12,7 +12,7 @@ REPO="${DEPLOY_REPO_DIR:-/home/debian/vanguard-stream}"; BRANCH="${DEPLOY_BRANCH
 STATE=/var/lib/vanguard; mkdir -p "$STATE" 2>/dev/null || true
 LASTF="$STATE/deployed-rev"; PREVF="$STATE/previous-rev"; PENDING="$STATE/mediamtx-restart-pending"
 DRY="${VG_DRY:-0}"; OWNER=$(stat -c %U "$REPO" 2>/dev/null || echo debian)
-log() { echo "$(date '+%F %T') deploy: $*"; }
+log() { printf 'ts=%s level=info component=deploy msg="%s"\n' "$(date -Is)" "${*//\"/\\\"}"; }
 run() { log "\$ $*"; [[ $DRY == 1 ]] || "$@"; }
 asowner() { log "\$ (as $OWNER) $*"; [[ $DRY == 1 ]] || sudo -u "$OWNER" -H "$@"; }
 notify() {