infra(gitea): recover the Actions runner before anything requires the gate

No runner is registered at repo, org or site level, so gate.yml has never executed.
PR #1 sat pending for 30.6 minutes across 122 polls and never reported. Requiring the
gate as a status check in that state would lock the repo permanently.

Adds runner-token-rotate.sh: mints a fresh instance-level registration token from the
Gitea API and writes it into the SOPS secret via sops set, without ever printing the
value.

Records the likely root cause, which a new token alone does NOT fix. act_runner
registers once and persists its identity in /data/.runner on the act-runner-data PVC.
If Gitea no longer holds a matching runner row, the pod starts, sees .runner, SKIPS
registration entirely, and polls with an identity Gitea does not recognise. Symptom:
zero runners, pod running, nothing obviously broken. Clearing the PVC is what forces a
genuine re-registration.

The README now sequences runner-first, enforcement-second, and requires CONFIRMING the
runner reports online rather than assuming it. That assumption is the whole defect:
DECISIONS-LOG recorded the runner as online on 2026-08-31 and nobody checked since.

Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>

infra/gitea/README.md

@@ -27,12 +27,28 @@ do not trust the API response**, since Gitea may let site admins bypass protecti
 It authenticates with the credential `git` already has stored for this host, and never
 prints the secret.
 
+## `runner-token-rotate.sh`
+
+Mints a fresh instance-level registration token from the Gitea API and writes it into
+`apps/wave-1/gitea-actions-runner-secret.sops.yaml` via `sops set`. **The token value is
+never printed.**
+
+    ./infra/gitea/runner-token-rotate.sh
+
+A fresh token is usually **not sufficient on its own**. `act_runner` registers exactly once
+and persists its identity in `/data/.runner` on the `act-runner-data` PVC. If Gitea no
+longer holds a matching runner row, the pod starts, sees `.runner`, **skips registration**,
+and polls with an identity Gitea does not recognise — so it never appears in the runner
+list. That is precisely the observed symptom: zero runners, pod running, no error anyone
+looks at. Clearing the PVC is what forces a real re-registration; the script prints the
+commands.
+
 ## Sequence — order matters
 
-1. **Get an Actions runner registered.** It is GitOps-managed
-   (`apps/wave-1/gitea-actions.yaml`, `apps/wave-1/gitea-actions-runner-secret.sops.yaml`),
-   so it is deployed but not registering — suspect a stale registration token in that
-   SOPS secret.
+1. **Get an Actions runner registered** — `runner-token-rotate.sh`, then clear the PVC so
+   the runner actually re-registers, then confirm it shows `online` in the API. Do not
+   skip the confirmation: the whole reason this went unnoticed is that a runner was
+   *recorded* as online without anyone checking.
 2. **Watch the gate actually report on a real PR**, and note the context name it produced.
 3. **Only then set `enable_status_check: true`** with that exact context.
 4. Add the human reviewer as a repo collaborator, then raise `required_approvals` to 1.