feat: Add twilio content templates (#12277)

Implements comprehensive Twilio WhatsApp content template support (Phase
1) enabling text, media, and quick reply templates with proper parameter
conversion, sync capabilities, and feature flag protection.

###  Features Implemented

  **Template Types Supported**

  - Basic Text Templates: Simple text with variables ({{1}}, {{2}})
  - Media Templates: Image/Video/Document templates with text variables
  - Quick Reply Templates: Interactive button templates
- Phase 2 (Future): List Picker, Call-to-Action, Catalog, Carousel,
Authentication templates

  **Template Synchronization**

- API Endpoint: POST
/api/v1/accounts/{account_id}/inboxes/{inbox_id}/sync_templates
  - Background Job: Channels::Twilio::TemplatesSyncJob
  - Storage: JSONB format in channel_twilio_sms.content_templates
  - Auto-categorization: UTILITY, MARKETING, AUTHENTICATION categories

 ###  Template Examples Tested


  #### Text template
```
  { "name": "greet", "language": "en" }
```
  #### Template with variables
```
  { "name": "order_status", "parameters": [{"type": "body", "parameters": [{"text": "John"}]}] }
```

  #### Media template with image
```
  { "name": "product_showcase", "parameters": [
    {"type": "header", "parameters": [{"image": {"link": "image.jpg"}}]},
    {"type": "body", "parameters": [{"text": "iPhone"}, {"text": "$999"}]}
  ]}
```
#### Preview

<img width="1362" height="1058" alt="CleanShot 2025-08-26 at 10 01
51@2x"
src="https://github.com/user-attachments/assets/cb280cea-08c3-44ca-8025-58a96cb3a451"
/>

<img width="1308" height="1246" alt="CleanShot 2025-08-26 at 10 02
02@2x"
src="https://github.com/user-attachments/assets/9ea8537a-61e9-40f5-844f-eaad337e1ddd"
/>

#### User guide

https://www.chatwoot.com/hc/user-guide/articles/1756195741-twilio-content-templates

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
Co-authored-by: Sivin Varghese <64252451+iamsivin@users.noreply.github.com>

app/javascript/dashboard/components-next/NewConversation/components/ContentTemplateForm.vue

@@ -0,0 +1,56 @@
+<script setup>
+import ContentTemplateParser from 'dashboard/components-next/content-templates/ContentTemplateParser.vue';
+import Button from 'dashboard/components-next/button/Button.vue';
+import { useI18n } from 'vue-i18n';
+
+defineProps({
+  template: {
+    type: Object,
+    default: () => ({}),
+  },
+});
+
+const emit = defineEmits(['sendMessage', 'back']);
+
+const { t } = useI18n();
+
+const handleSendMessage = payload => {
+  emit('sendMessage', payload);
+};
+
+const handleBack = () => {
+  emit('back');
+};
+</script>
+
+<template>
+  <div
+    class="absolute top-full mt-1.5 max-h-[30rem] overflow-y-auto ltr:left-0 rtl:right-0 flex flex-col gap-4 px-4 pt-6 pb-5 items-start w-[28.75rem] h-auto bg-n-solid-2 border border-n-strong shadow-sm rounded-lg"
+  >
+    <div class="w-full">
+      <ContentTemplateParser
+        :template="template"
+        @send-message="handleSendMessage"
+        @back="handleBack"
+      >
+        <template #actions="{ sendMessage, goBack, disabled }">
+          <div class="flex gap-3 justify-between items-end w-full h-14">
+            <Button
+              :label="t('CONTENT_TEMPLATES.FORM.BACK_BUTTON')"
+              color="slate"
+              variant="faded"
+              class="w-full font-medium"
+              @click="goBack"
+            />
+            <Button
+              :label="t('CONTENT_TEMPLATES.FORM.SEND_MESSAGE_BUTTON')"
+              class="w-full font-medium"
+              :disabled="disabled"
+              @click="sendMessage"
+            />
+          </div>
+        </template>
+      </ContentTemplateParser>
+    </div>
+  </div>
+</template>