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/uploadImageToAssets.js

@@ -154,7 +154,7 @@ export function registerUploadImageToAssetsTool(server) {
 
                 // Upload using saveFileBuilder
                 const uploadResult = await saveFileBuilder({
-                    web_url: credentials.api_web_url || credentials.web_url,
+                    credentials,
                     token: credentials.token,
                     tokenHash: credentials.tokenHash,
                     path: assetsPath,