fix(template): send parameter_name for named-variable templates

WhatsApp API returns "(#100) Invalid parameter — Parameter name is
missing or empty" for templates that use named variables.

- chat.php sendTemplate(): collect params as [{name, value}] objects
  using data-var-index as the parameter name
- WhatsAppService::sendTemplateMessage(): handle {name, value} objects
  in the indexed-array path by emitting {type, parameter_name, text}
  (backward-compatible — plain strings still work as positional params)

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

services/WhatsAppService.php

@@ -181,6 +181,13 @@ class WhatsAppService
                         $bpCopy = $bp;
                         unset($bpCopy['name']);
                         $normalizedBody[] = $bpCopy; // already detailed
+                    } elseif (is_array($bp) && isset($bp['name'], $bp['value'])) {
+                        // {name: 'param_name', value: 'text'} — include parameter_name for named-variable templates
+                        $normalizedBody[] = [
+                            'type'           => 'text',
+                            'parameter_name' => (string)$bp['name'],
+                            'text'           => (string)$bp['value'],
+                        ];
                     } elseif (is_string($bp) || is_numeric($bp)) {
                         $normalizedBody[] = [
                             'type' => 'text',