feat: log aggregation — the machine ships its logs to Loki

The gameplay logs sat on /dump on the machine, readable only over SSH. Now
they land in Loki for query and tail:

- k8s/loki/loki.yaml: Loki 3.4.4 monolithic on the home cluster's monitoring
  namespace — filesystem storage on CephFS, 30-day retention, traefik ingress
  at loki.k8s-home.lqx.net with a cert-manager cert, Grafana datasource
  auto-registered via the sidecar. reject_old_samples_max_age is a year:
  the machines backfill their history on first ship.
- shipper/: logshipper, a ~300-line static Go service for the machine. Tails
  /dump/mode.log and /dump/switch.log, batches, pushes to Loki's push API.
  Per-file offsets are saved only after a successful push (down Loki =
  retry-then-catch-up, never loss); first run starts at each file's end,
  SHIP_FROM_START=1 ships history; truncation is noticed. Lines keep their
  own RFC 3339 stamp as the Loki timestamp; unstamped lines (the boot
  banner) inherit the next stamped line's, so a stream never starts at
  "now" and jumps back. After a backfill it calls /flush — old entries are
  invisible in the ingester's head until they reach the store (found the
  hard way: Loki answers 204 to an old entry on a new stream and then never
  serves it). Labels: job=pinball, machine, source, game (from the boot
  line). /etc/init.d/log_shipper runs it at boot.

Deployed: Loki is live and verified (query through the ingress). The shipper
is verified end-to-end against the cluster from this Mac; the machine was
unreachable at deploy time — the README has the install commands.

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

shipper/init.d/log_shipper

@@ -0,0 +1,21 @@
+#!/bin/sh
+# log_shipper - tail /dump/*.log and push them to Loki (see shipper/README.md).
+# Config comes from the environment; defaults in the binary match the machine.
+
+case "$1" in
+  start)
+    start-stop-daemon -S -b -m -p /run/logshipper.pid -x /usr/local/bin/logshipper
+    ;;
+  stop)
+    start-stop-daemon -K -p /run/logshipper.pid
+    ;;
+  restart)
+    "$0" stop
+    sleep 1
+    "$0" start
+    ;;
+  *)
+    echo "usage: $0 {start|stop|restart}"
+    exit 1
+    ;;
+esac