fix: Social FB — Page token + aviso si el Meta token no tiene pages_*

El token de ads no sirve para /posts; intentamos Page Access Token y explicamos los permisos necesarios.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/lib/ads-discovery.ts

@@ -81,7 +81,7 @@ export async function saveMetaAccessToken(token: string): Promise<{
     access_token: clean,
     account_email: me.name || me.id || null,
     expires_at: null,
-    scopes: 'ads_read,ads_management,business_management',
+    scopes: 'ads_read,ads_management,business_management,pages_show_list,pages_read_engagement,pages_read_user_content,instagram_basic,instagram_manage_insights',
     updated_at: new Date().toISOString(),
     meta: { graph_id: me.id || null, saved_via: 'paste' },
   };