fix(ci): deploy Caddyfile via the runner's own bind, not docker-from-docker

Runs 137-139 all failed at "cp: can't stat '/dest/Caddyfile/Caddyfile'".
The step bound "$PWD/Caddyfile" into an alpine container, but the job
workspace is a Docker volume -- the daemon resolved that source on the
HOST, found nothing, and created an empty directory there instead (it
left a root-owned /workspace/ginnoir/homelabstack/Caddyfile/ on valhalla).
So alpine got a directory as its copy source and cp failed, leaving the
live Caddyfile stale since run 136.

The premise was wrong: act_runner's container.options already binds
/config/caddy and /var/run/docker.sock into every job container. Copy
straight into the bind and reload through the Docker Engine API over the
socket -- which also drops the 40s apt-get install of docker.io.

Uses cp rather than mv/install because /config/caddy/Caddyfile is bound
into the caddy container as a single file, so the bind follows the inode.

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

.gitea/workflows/deploy-caddy.yml

@@ -17,15 +17,37 @@ jobs:
 
       - name: Push Caddyfile and reload Caddy
         run: |
-          # Job containers do NOT inherit the runner's /config/caddy bind.
-          # Docker-from-Docker with a host bind is the reliable path: the
-          # volume source is resolved on valhalla, not inside the job container.
-          # (Direct `cp /config/caddy/...` only works on the runner container
-          # itself, which is not where this step runs.)
-          apt-get update -qq && apt-get install -y -qq docker.io
-          docker run --rm \
-            -v /config/caddy:/dest \
-            -v "$PWD/Caddyfile:/src/Caddyfile:ro" \
-            alpine:3.20 \
-            cp /src/Caddyfile /dest/Caddyfile
-          docker exec caddy caddy reload --config /etc/caddy/Caddyfile
+          set -euo pipefail
+
+          # The runner (act_runner config.yaml `container.options`) binds
+          # /config/caddy and /var/run/docker.sock into every job container,
+          # so both are already here -- no docker-from-docker, no docker CLI.
+          #
+          # Do NOT bind $PWD into a `docker run`: the workspace is a Docker
+          # volume, so the daemon resolves the source on the HOST, finds
+          # nothing, and creates an empty directory there instead. That is
+          # what broke runs 137-139.
+          #
+          # cp (not mv/install): /config/caddy/Caddyfile is bind-mounted into
+          # the caddy container as a single FILE, so the bind follows the
+          # inode. Replacing the inode would silently detach caddy from it.
+          cp Caddyfile /config/caddy/Caddyfile
+
+          # Reload via the Docker Engine API over the mounted socket.
+          SOCK=/var/run/docker.sock
+          api() { curl -sS --unix-socket "$SOCK" "$@"; }
+          json() { node -e 'let d="";process.stdin.on("data",c=>d+=c).on("end",()=>console.log(JSON.parse(d)[process.argv[1]]))' "$1"; }
+
+          EXEC_ID=$(api -X POST -H 'Content-Type: application/json' \
+            -d '{"AttachStdout":true,"AttachStderr":true,"Cmd":["caddy","reload","--config","/etc/caddy/Caddyfile"]}' \
+            "http://localhost/containers/caddy/exec" | json Id)
+
+          # Strip the stream-multiplexing frame headers from the output.
+          api -X POST -H 'Content-Type: application/json' -d '{"Detach":false,"Tty":false}' \
+            "http://localhost/exec/$EXEC_ID/start" | tr -d '\000-\010\013\014\016-\037'
+          echo
+
+          # caddy reload validates before applying; a bad Caddyfile fails here.
+          CODE=$(api "http://localhost/exec/$EXEC_ID/json" | json ExitCode)
+          echo "caddy reload exit code: $CODE"
+          exit "$CODE"