[MCP-UI] Proxy and Better Message Handling (#5487)

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
Co-authored-by: Alex Hancock <alexhancock@block.xyz>
Co-authored-by: Zane <75694352+zanesq@users.noreply.github.com>

ui/desktop/openapi.json

@@ -1042,6 +1042,33 @@
         }
       }
     },
+    "/mcp-ui-proxy": {
+      "get": {
+        "tags": [
+          "super::routes::mcp_ui_proxy"
+        ],
+        "operationId": "mcp_ui_proxy",
+        "parameters": [
+          {
+            "name": "secret",
+            "in": "query",
+            "description": "Secret key for authentication",
+            "required": true,
+            "schema": {
+              "type": "string"
+            }
+          }
+        ],
+        "responses": {
+          "200": {
+            "description": "MCP UI proxy HTML page"
+          },
+          "401": {
+            "description": "Unauthorized - invalid or missing secret"
+          }
+        }
+      }
+    },
     "/recipes/create": {
       "post": {
         "tags": [