feat: let the runner build and the cluster pull from the Forgejo registry

- Runner egress: allow 192.168.1.160/32:443. forgejo.riotpiao.com resolves to
  the ingress LB, inside the 192.168.1.0/24 block the NetworkPolicy denies, so
  docker push hung until timeout.
- dind CA: also mount homelab-ca at /etc/docker/certs.d/forgejo.riotpiao.com/,
  the path dockerd actually reads for per-registry trust.
- Pull secret: dockerconfigjson for the api namespace; /v2/ answers 401.
- AppProject: allow the Forgejo repo as a source for api-gw.

k8s/argocd/secrets/secret-generator.yaml

@@ -11,6 +11,7 @@ files:
   - agent-pod-ssh-key.enc.yaml
   - authentik-secrets.enc.yaml
   - cloudflare-secrets.enc.yaml
+  - forgejo-registry-pull.enc.yaml
   - forgejo-runner-token.enc.yaml
   - forgejo-secrets.enc.yaml
   - grafana-oidc-secrets.enc.yaml