feat(ci): add GitOps pipeline with Gitea Actions and ArgoCD

- Add Gitea Actions workflow for building and pushing Docker images
- Configure ArgoCD Application for auto-sync deployment
- Update Helm values to use Gitea container registry
- Add setup documentation for GitOps configuration

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

argocd/SETUP.md

@@ -0,0 +1,104 @@
+# ArgoCD GitOps Setup for TaskPlaner
+
+This guide sets up automatic deployment of TaskPlaner using GitOps with ArgoCD and Gitea.
+
+## Prerequisites
+
+- Kubernetes cluster access
+- Gitea instance with Packages (Container Registry) enabled
+- Gitea Actions runner configured
+
+## 1. Install ArgoCD
+
+```bash
+kubectl create namespace argocd
+kubectl apply -n argocd -f https://raw.githubusercontent.com/argoproj/argo-cd/stable/manifests/install.yaml
+```
+
+Wait for ArgoCD to be ready:
+```bash
+kubectl wait --for=condition=available deployment/argocd-server -n argocd --timeout=300s
+```
+
+## 2. Configure Gitea Registry Secrets
+
+### For Gitea Actions (push access)
+
+In Gitea repository settings, add these secrets:
+- `REGISTRY_USERNAME`: Your Gitea username
+- `REGISTRY_PASSWORD`: A Gitea access token with `write:package` scope
+
+### For Kubernetes (pull access)
+
+Create an image pull secret:
+```bash
+kubectl create secret docker-registry gitea-registry-secret \
+  --docker-server=git.kube2.tricnet.de \
+  --docker-username=YOUR_USERNAME \
+  --docker-password=YOUR_ACCESS_TOKEN \
+  -n default
+```
+
+## 3. Configure ArgoCD Repository Access
+
+Add the Gitea repository to ArgoCD:
+```bash
+# Get ArgoCD admin password
+kubectl -n argocd get secret argocd-initial-admin-secret -o jsonpath="{.data.password}" | base64 -d; echo
+
+# Port forward to access ArgoCD UI
+kubectl port-forward svc/argocd-server -n argocd 8080:443
+
+# Or use CLI
+argocd login localhost:8080 --insecure
+argocd repo add https://git.kube2.tricnet.de/tho/taskplaner.git \
+  --username YOUR_USERNAME \
+  --password YOUR_ACCESS_TOKEN
+```
+
+## 4. Deploy the ArgoCD Application
+
+```bash
+kubectl apply -f argocd/application.yaml
+```
+
+Note: Edit `application.yaml` first to remove the example Secret or replace `REPLACE_WITH_BASE64_ENCODED_USERNAME_COLON_PASSWORD` with actual credentials.
+
+## 5. Verify Deployment
+
+```bash
+# Check ArgoCD application status
+kubectl get applications -n argocd
+
+# Watch sync status
+argocd app get taskplaner
+
+# Check pods
+kubectl get pods -l app.kubernetes.io/name=taskplaner
+```
+
+## Workflow
+
+1. Push code to `master` branch
+2. Gitea Actions builds Docker image and pushes to registry
+3. Workflow updates `helm/taskplaner/values.yaml` with new image tag
+4. ArgoCD detects change and auto-syncs deployment
+
+## Troubleshooting
+
+### Image Pull Errors
+```bash
+kubectl describe pod -l app.kubernetes.io/name=taskplaner
+```
+Check if the image pull secret is correctly configured.
+
+### ArgoCD Sync Issues
+```bash
+argocd app sync taskplaner --force
+argocd app logs taskplaner
+```
+
+### Actions Runner Issues
+```bash
+kubectl logs -n gitea -l app=act-runner -c runner
+```