G7: CI runners with real isolation, and the gate as a workflow

I-5 says runners execute untrusted code and must be isolated by machine
boundary. act_runner needs a Docker daemon to start job containers, and the
tempting move — what every published example does — is to mount the host's
/var/run/docker.sock. That hands every workflow, including whatever a
transitive dependency's postinstall script feels like doing, the ability to
start a privileged container mounting / — root on Grant's workstation.

Instead the runner talks to its OWN dind daemon:
  - runner (TRUSTED, the act_runner daemon) sits on the forge network only to
    collect jobs from gitea:3000
  - dind and every job container it spawns are UNTRUSTED, on a private network
    with no route to the forge, its Postgres, or its .env
  - jobs cannot bind-mount from the daemon host (valid_volumes: []) and are not
    handed the runner's own socket (docker_host: -)
  - separate compose project, cpu/memory bounded — Veron 1 is Grant's
    workstation, not a dedicated build box

The gate itself now runs as a workflow, including the migration round-trip that
already caught two bugs review did not, and the I-12 check that a COMMIT_SHA
env override cannot change what /version reports.

Labels are explicit and pinned. A workflow naming a label nobody provides
queues forever and presents as a hung CI system rather than a typo — which is
what ubuntu-latest does on every windy-registry run today.

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

deploy/runner/config.yaml

@@ -0,0 +1,38 @@
+# act_runner configuration (G7.1).
+#
+# Labels are EXPLICIT and PINNED. `ubuntu-latest` is banned (G7.5): all four
+# windy-registry workflows use it and every single run fails, because a
+# self-hosted runner has no such label unless you invent one. A workflow that
+# names a label nobody provides queues forever and looks like a hung CI system
+# rather than a typo.
+
+log:
+  level: info
+
+runner:
+  file: /data/.runner
+  capacity: 4          # concurrent jobs; Veron has 24 cores, dind is capped at 12
+  timeout: 30m
+  shutdown_timeout: 3m
+  insecure: false
+  fetch_timeout: 5s
+  fetch_interval: 2s
+  labels:
+    - "veron-1:docker://catthehacker/ubuntu:act-22.04"
+    - "linux-x64:docker://catthehacker/ubuntu:act-22.04"
+
+cache:
+  enabled: true
+  dir: /data/cache
+
+container:
+  # Job containers join the dind daemon's own bridge. NOT the forge network:
+  # untrusted code must never be able to reach the forge's Postgres or its
+  # environment (I-5).
+  network: bridge
+  privileged: false
+  options:
+  workdir_parent: /workspace
+  valid_volumes: []      # a job cannot bind-mount anything from the daemon host
+  docker_host: "-"       # do NOT expose the runner's own docker socket to jobs
+  force_pull: false