Add ArgoCD and Gitea for GitOps workflow implementation

- Deploy ArgoCD with Helm for GitOps continuous delivery
  * Configure LoadBalancer and Ingress access on LAN
  * Enable ArgoCD Image Updater for automatic "latest" tag updates
  * Simplified RBAC for single-user homelab environment

- Deploy Gitea as self-hosted Git server for local repositories
  * PostgreSQL backend with NFS persistent storage
  * SSH and HTTP access via MetalLB LoadBalancer
  * Integration guides for ArgoCD GitOps workflows

- Add example ArgoCD Application with auto-image updates
- Include comprehensive migration guides from Helm to GitOps
- Maintain compatibility with existing Helm-based deployments

🤖 Generated with [Claude Code](https://claude.ai/code)

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

argocd-example-app.yaml

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+# Example ArgoCD Application with Image Auto-Update
+# This demonstrates how to set up your existing Helm applications in ArgoCD
+# with automatic "latest" tag updates
+
+apiVersion: argoproj.io/v1alpha1
+kind: Application
+metadata:
+  name: plex-example
+  namespace: argocd
+  annotations:
+    # Enable automatic image updates for Plex
+    argocd-image-updater.argoproj.io/image-list: plex=ghcr.io/k8s-at-home/plex:latest
+    # Use 'newest-build' strategy for latest images
+    argocd-image-updater.argoproj.io/plex.update-strategy: newest-build
+    # Write back to ArgoCD (for testing - production should use git method)
+    argocd-image-updater.argoproj.io/write-back-method: argocd
+spec:
+  project: default
+  source:
+    # Point to your repository (replace with your actual Git repo)
+    repoURL: https://github.com/munnerz/kube-plex
+    path: charts/kube-plex
+    targetRevision: HEAD
+    helm:
+      valueFiles:
+        # This would reference your existing plex_values.yml
+        # For now, this is just an example structure
+        - values.yaml
+      parameters:
+        - name: image.tag
+          value: latest
+  destination:
+    server: https://kubernetes.default.svc
+    namespace: plex
+  syncPolicy:
+    automated:
+      prune: true
+      selfHeal: true
+    syncOptions:
+    - CreateNamespace=true