feat: two-message post-selection flow in multi-company pre-menu

After user selects a company, send short confirmation text then reset
bot_context and trigger BotRouter with empty message to fire the greeting.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

admin/v1/WpWebhook.php

@@ -209,9 +209,27 @@ class WpWebhook
             $company['_permission_type'] = self::getPermissionType($companies, $selectedId);
             self::$currentCompany = $company;
             $displayName = $company['display_name'] ?: $company['name'];
-            WhatsAppSender::sendText($from, "✅ Conectado con *{$displayName}*.\nEscribe tu consulta o *menú* para ver las opciones.", $phoneNumberId);
+
+            // Mensaje 1: confirmación
+            WhatsAppSender::sendText($from, "✅ Conectado con *{$displayName}*.", $phoneNumberId);
+
+            // Mensaje 2: greeting del bot — reset contexto y disparar con mensaje vacío
+            $botCtx = ConversationContext::getOrCreate((int)$selectedId, $from, 'normal');
+            ConversationContext::reset((int)$botCtx['id']);
+            $synthCtx = [
+                'from'            => $from,
+                'name'            => $name,
+                'message_id'      => 'mc_' . uniqid(),
+                'type'            => 'text',
+                'timestamp'       => time(),
+                'phone_number_id' => $phoneNumberId,
+                'display_phone'   => '',
+                'permission_type' => self::getPermissionType($companies, $selectedId),
+            ];
+            BotRouter::route($company, $synthCtx, '', 'text');
+
             self::log('INFO', "Multi-empresa: {$from} seleccionó empresa #{$selectedId} ({$displayName})");
-            return false; // el clic en botón no se procesa como comando del bot
+            return false;
         }
 
         // 2. Keyword de reinicio → borrar sesión y mostrar pre-menú