Move Foldergram media dir; add batch CT creator

Change Foldergram installation to store media and config under /opt/foldergram_media (create media dir, write env file there, update systemd EnvironmentFile). Update ct/foldergram.sh to remove temporary backup/restore during updates. Update json/foldergram.json config_path and add an info note about where to place media. Add tools/pve/ct-batch-create.sh — a new Proxmox CT batch-creator script (interactive/unattended modes, caching, storage selection) to download and deploy multiple community-scripts CTs.

json/foldergram.json

@@ -17,7 +17,7 @@
     {
       "type": "default",
       "script": "ct/foldergram.sh",
-      "config_path": "/opt/foldergram/foldergram.env",
+      "config_path": "/opt/foldergram_media/foldergram.env",
       "resources": {
         "cpu": 1,
         "ram": 2048,
@@ -31,5 +31,10 @@
     "username": null,
     "password": null
   },
-  "notes": []
-}
+  "notes": [
+    {
+      "text": "Media data (gallery, database, thumbnails, previews) is stored under /opt/foldergram_media. Place your photos and videos in /opt/foldergram_media/gallery.",
+      "type": "info"
+    }
+  ]
+}