Fix upload_image_to_assets 404 en Forge (header Host) + guard data-URI

- saveFileBuilder (fileBuilder.js) hacía POST directo a viewer_functions.php
  sin header Host -> en Forge (api_web_url interno http://web:80) Apache
  servía el vhost por defecto -> 404. Ahora delega en
  AcaiHttpClient.postViewerAction, que resuelve api_web_url + Host:
  forge_host (igual que el resto de tools). Pasa credentials completo.
- upload_record_image: rechaza data-URI/base64 con error claro (antes
  derivaba el nombre del base64 -> "File name too long" en mcp_respond.php).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

mcp-server/tools/media/upload.js

@@ -119,6 +119,25 @@ export function registerUploadRecordImageTool(server) {
                 );
                 if (validationError) return validationError;
 
+                // Rechazar data-URI / base64 crudo: derivar el nombre de fichero
+                // del base64 produce nombres de miles de chars que revientan
+                // file_put_contents ("File name too long"). Exigir URL http real.
+                const trimmedImage = imageUrl.trim();
+                const isHttpUrl = /^https?:\/\//i.test(trimmedImage);
+                const isFsPath = trimmedImage.startsWith("/") && !trimmedImage.startsWith("//");
+                if (!isHttpUrl && !isFsPath) {
+                    return {
+                        content: [{
+                            type: "text",
+                            text: JSON.stringify({
+                                error: "imageUrl must be an http(s) URL, not a data URI or raw base64. " +
+                                    "First upload the image with the 'upload_image_to_assets' tool and pass the returned imageUrl here."
+                            }, null, 2)
+                        }],
+                        isError: true,
+                    };
+                }
+
                 const projectSlug = path.basename(resolveCurrentProjectDir());
 
                 // Intentar via Python server (tiene sync + optimizacion)