implemented the Ticker module with a native ProseMirror document renderer and integrated API support for structured content, navigation trees, and proxied files

test/widget/prosemirror/fixtures/callout.json

@@ -0,0 +1,51 @@
+{
+  "type": "doc",
+  "content": [
+    {
+      "type": "callout",
+      "attrs": {
+        "variant": "info"
+      },
+      "content": [
+        {
+          "type": "paragraph",
+          "attrs": {
+            "textAlign": "left"
+          },
+          "content": [
+            {
+              "type": "text",
+              "text": "Ein wichtiger Hinweis."
+            }
+          ]
+        }
+      ]
+    },
+    {
+      "type": "callout",
+      "attrs": {
+        "variant": "warning"
+      },
+      "content": [
+        {
+          "type": "paragraph",
+          "attrs": {
+            "textAlign": "left"
+          },
+          "content": [
+            {
+              "type": "text",
+              "text": "Achtung."
+            }
+          ]
+        }
+      ]
+    },
+    {
+      "type": "paragraph",
+      "attrs": {
+        "textAlign": null
+      }
+    }
+  ]
+}