feat(diun): add auto-update infrastructure

- Custom DIUN image with git/ssh for script notifier
- Auto-update script: detects new image versions, updates .tf files, pushes
- ESO secret for git credentials, persistent repo clone PVC
- GHA workflow to build custom DIUN image
- Skips databases and CI/CD-managed images automatically

.github/workflows/build-diun.yml

@@ -0,0 +1,28 @@
+name: Build Custom DIUN Image
+
+on:
+  push:
+    branches: [master]
+    paths:
+      - 'stacks/diun/Dockerfile'
+  workflow_dispatch:
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: docker/setup-buildx-action@v3
+
+      - uses: docker/login-action@v3
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+
+      - uses: docker/build-push-action@v6
+        with:
+          context: stacks/diun
+          platforms: linux/amd64
+          push: true
+          tags: viktorbarzin/diun:latest