feat(ops): self-update script, systemd units, README install guide, recovery runbook

- deploy/ops-dashboard-updater/update.sh: git pull → docker build → force-recreate → smoke-test
- deploy/ops-dashboard-updater/install.sh: installs script + systemd units to host
- ops-dashboard-updater.service / .timer: oneshot + daily 03:00 scheduled trigger
- README.md: Installation and Configuration sections (env files, ops-agent, updater)
- docs/runbooks/recovery.md: agent-crash, DB corruption/restore, container failure, cert expiry

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

deploy/ops-dashboard-updater/ops-dashboard-updater.timer

@@ -0,0 +1,11 @@
+[Unit]
+Description=Scheduled self-update for ops-dashboard (optional)
+
+[Timer]
+# Check for updates every day at 03:00 local time.
+# Disable this timer if you prefer manual-only updates via SSH.
+OnCalendar=*-*-* 03:00:00
+Persistent=true
+
+[Install]
+WantedBy=timers.target