refactor: bootstrap/infra/ci separation (#27)

- Create bootstrap/ dir: cert-manager, traefik-routes, argo-rollouts,
  kargo, kargo-*-pipeline (not managed by Kargo promotion)
- infra/ now only: gitea, gitea-custom (promoted by Kargo)
- ci/ unchanged: gitea-runner (promoted by Kargo)
- Split kargo/credentials/ into dev/ and prod/ with separate ksops generators
- Remove kargo-credentials from AppSet (managed by Pulumi Go code)
- Update infra Warehouse: only gitea (was also argo-rollouts, cert-manager)
- Update infra Stage dev: only yaml-update for gitea version
- Fix test-env warehouse: valid subscription instead of empty array
- Update step numbers: bootstrap 1-5, infra 1-2

kargo/infra/warehouse.yaml

@@ -5,16 +5,6 @@ metadata:
   namespace: infra
 spec:
   subscriptions:
-    - chart:
-        repoURL: https://charts.jetstack.io
-        name: cert-manager
-        semverConstraint: ">=1.17.0"
-        discoveryLimit: 5
-    - chart:
-        repoURL: https://argoproj.github.io/argo-helm
-        name: argo-rollouts
-        semverConstraint: ">=2.39.0"
-        discoveryLimit: 5
     - chart:
         repoURL: https://dl.gitea.com/charts
         name: gitea