Deploy from GitHub with a systemd timer instead of Gitea Actions

Cosmos keeps a deploy-only clone of the GitHub repo. gk-deploy.timer runs
pull-and-deploy.sh every 5 minutes: it fetches master and, when it has
moved, runs deploy.sh (build, check, restart, roll back if unhealthy). A
commit that failed is not retried until master moves (FORCE=1 retries), and
DEPLOY_HEALTHCHECK_URL turns red on a failed fetch or deploy. Removes the
Gitea workflow and updates the runbook, README and inventory note.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012aSbo2D1qP8cMFQCykf7kx

deploy/gk-deploy.service

@@ -0,0 +1,15 @@
+# Deploys GregKilmer.com from the GitHub clone when master moves.
+# Install: sudo cp deploy/gk-deploy.{service,timer} /etc/systemd/system/
+#          sudo systemctl daemon-reload && sudo systemctl enable --now gk-deploy.timer
+# Logs: journalctl -u gk-deploy. See docs/deploy.md.
+[Unit]
+Description=Deploy GregKilmer.com from GitHub
+Wants=network-online.target
+After=network-online.target docker.service
+
+[Service]
+Type=oneshot
+User=greg
+Environment=GK_STACK_DIR=/home/greg/homelab/gregkilmer
+ExecStart=/home/greg/homelab/gregkilmer/repo/deploy/pull-and-deploy.sh
+TimeoutStartSec=30min