feat(schema): templateProps + schemaRef + designGuide + blockStudio

Vorbereitung fuer dynamische Pagebuilder-Bloecke (nova feature/dynamic-pagebuilder-blocks):
- field-meta: Widget templateProps, meta.schemaRef {ref?, field required}
  (statische subFields / Sibling-Schema / FK-Schema fuer type:any-Felder)
- collection-meta: meta.designGuide (i18nText) als KI-Hinweis pro Collection
- collection-meta: viewHint.blockStudio {previewField, lint, renderer.file}
  (Spezial-View wie navigation/media, inkl. oneOf-Zweig)

schemas/config/field-meta.schema.json

@@ -35,6 +35,7 @@
         "foreignMedia",
         "pagebuilder",
         "pageBuilder",
+        "templateProps",
         "containerLessObject",
         "containerLessObjectArray",
         "color"
@@ -299,6 +300,21 @@
         }
       }
     },
+    "schemaRef": {
+      "type": "object",
+      "additionalProperties": false,
+      "properties": {
+        "ref": {
+          "type": "string"
+        },
+        "field": {
+          "type": "string"
+        }
+      },
+      "required": [
+        "field"
+      ]
+    },
     "openapi": {
       "$ref": "openapi.schema.json#/definitions/fieldOpenapi"
     }