Update URL type to avoid string-ifying and creating complexity

docs/resources/llama-stack-spec.html

@@ -2893,9 +2893,16 @@
                 ]
             },
             "URL": {
-                "type": "string",
-                "format": "uri",
-                "pattern": "^(https?://|file://|data:)"
+                "type": "object",
+                "properties": {
+                    "uri": {
+                        "type": "string"
+                    }
+                },
+                "additionalProperties": false,
+                "required": [
+                    "uri"
+                ]
             },
             "UserMessage": {
                 "type": "object",

docs/resources/llama-stack-spec.yaml

@@ -3105,9 +3105,13 @@ components:
       title: A single turn in an interaction with an Agentic System.
       type: object
     URL:
-      format: uri
-      pattern: ^(https?://|file://|data:)
-      type: string
+      additionalProperties: false
+      properties:
+        uri:
+          type: string
+      required:
+      - uri
+      type: object
     UnregisterDatasetRequest:
       additionalProperties: false
       properties: