fix: vendor Tekton release.yaml for proper ArgoCD management

ROOT CAUSE:
- tektoncd/pipeline config/ dir uses ko:// image refs (build-time placeholders)
- ArgoCD synced the raw dev manifests → InvalidImageName on all pods
- tektoncd/operator requires its own CRDs and controller (too heavy)
- Tekton has no official Helm chart

FIX:
- Vendor the pre-built release.yaml (v0.68.0) into k8s/infra/tekton/
- Point ArgoCD Application at our own repo (forgejo)
- Release contains real container images (ghcr.io/tektoncd/pipeline/*)
- Remove external tektoncd repo from AppProject (not needed)

TO UPGRADE TEKTON:
  1. Download new release from github.com/tektoncd/pipeline/releases
  2. Replace k8s/infra/tekton/release.yaml
  3. Commit — ArgoCD syncs automatically

k8s/argocd/projects/homelab-project.yaml

@@ -45,8 +45,6 @@ spec:
     - https://stakater.github.io/stakater-charts
     # ArgoCD ecosystem charts
     - https://argoproj.github.io/argo-helm
-    # Tekton Pipelines (CNCF CI/CD) — uses tektoncd/operator
-    - https://github.com/tektoncd/operator.git
   destinations:
     - server: https://kubernetes.default.svc
       namespace: "*"