examples/media-stats-ui: fix Transform source key; add file_name column

Signed-off-by: NotAShelf <raf@notashelf.dev>
Change-Id: I4c741e4b36708f2078fed8154d7341de6a6a6964

examples/plugins/media-stats-ui/pages/stats.json

@@ -64,6 +64,10 @@
               "filterable": true,
               "page_size": 10,
               "columns": [
+                {
+                  "key": "file_name",
+                  "header": "Filename"
+                },
                 {
                   "key": "title",
                   "header": "Title"
@@ -120,13 +124,9 @@
       "path": "/api/v1/media"
     },
     "type-breakdown": {
-      "type": "static",
-      "value": [
-        { "type": "Audio",    "count": 0 },
-        { "type": "Video",    "count": 0 },
-        { "type": "Image",    "count": 0 },
-        { "type": "Document", "count": 0 }
-      ]
+      "type": "transform",
+      "source": "stats",
+      "expression": "stats.media_by_type"
     }
   }
 }