security: clean repository without media files and sensitive data

- Removed area/ directory with 816MB of media files
- Removed sensitive FTP credentials from Git history
- Implemented .env.upload system for secure deployments
- Added comprehensive .gitignore for future protection

This commit represents a clean slate with all sensitive data removed.

backend/storage/data/viewers.json

@@ -0,0 +1,7 @@
+{
+  "Viewer_Sample": {
+    "pass": "fc8b22f41628b89ce8102e705d1734kf",
+    "dir": "Paramount",
+    "tab": "Beispiele"
+  }
+}