feat(ci): add Nextcloud version matrix (NC 31, 32, 33)

- Add cross-product matrix (3 versions x 4 auth modes = 12 CI jobs)
- Parameterize Nextcloud image in docker-compose.yml via NEXTCLOUD_IMAGE env var
- Pin NC 31.0.8, 32.0.6, 33.0.0 with SHA digests in workflow
- Add Renovate customManagers to auto-update NC images in workflow
- Fix Astrolabe install hook to prefer volume mount over app store
- Bump Astrolabe submodule to support NC 33 (max-version 31→33)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app-hooks/post-installation/20-install-astrolabe-app.sh

@@ -2,12 +2,30 @@
 
 set -euox pipefail
 
-echo "Installing Astrolabe app from app store..."
+echo "Installing Astrolabe app..."
 
-if [ -d /var/www/html/custom_apps/astrolabe ]; then
+# Check if development astrolabe app is mounted at /opt/apps/astrolabe
+if [ -d /opt/apps/astrolabe ]; then
+    echo "Development astrolabe app found at /opt/apps/astrolabe"
+
+    # Remove any existing astrolabe app in custom_apps (from app store or old symlink)
+    if [ -e /var/www/html/custom_apps/astrolabe ]; then
+        echo "Removing existing astrolabe in custom_apps..."
+        rm -rf /var/www/html/custom_apps/astrolabe
+    fi
+
+    # Create symlink from custom_apps to the mounted development version
+    # Per Nextcloud docs: apps outside server root need symlinks in server root
+    echo "Creating symlink: custom_apps/astrolabe -> /opt/apps/astrolabe"
+    ln -sf /opt/apps/astrolabe /var/www/html/custom_apps/astrolabe
+
+    echo "Enabling astrolabe app from /opt/apps (development mode via symlink)"
+    php /var/www/html/occ app:enable astrolabe
+elif [ -d /var/www/html/custom_apps/astrolabe ]; then
     echo "astrolabe app directory found in custom_apps (already installed)"
     php /var/www/html/occ app:enable astrolabe
 else
+    echo "astrolabe app not found, installing from app store..."
     php /var/www/html/occ app:install astrolabe
     php /var/www/html/occ app:enable astrolabe
 fi