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/widgets/conversation/ContentTemplates/ContentTemplatesModal.vue

@@ -0,0 +1,97 @@
+<script setup>
+import { ref, computed } from 'vue';
+import { useI18n } from 'vue-i18n';
+import TemplatesPicker from './ContentTemplatesPicker.vue';
+import TemplateParser from '../../../../components-next/content-templates/ContentTemplateParser.vue';
+import Button from 'dashboard/components-next/button/Button.vue';
+
+const props = defineProps({
+  show: {
+    type: Boolean,
+    default: false,
+  },
+  inboxId: {
+    type: Number,
+    default: undefined,
+  },
+});
+
+const emit = defineEmits(['onSend', 'cancel', 'update:show']);
+
+const { t } = useI18n();
+
+const selectedContentTemplate = ref(null);
+
+const localShow = computed({
+  get() {
+    return props.show;
+  },
+  set(value) {
+    emit('update:show', value);
+  },
+});
+
+const modalHeaderContent = computed(() => {
+  return selectedContentTemplate.value
+    ? t('CONTENT_TEMPLATES.MODAL.TEMPLATE_SELECTED_SUBTITLE', {
+        templateName: selectedContentTemplate.value.friendly_name,
+      })
+    : t('CONTENT_TEMPLATES.MODAL.SUBTITLE');
+});
+
+const pickTemplate = template => {
+  selectedContentTemplate.value = template;
+};
+
+const onResetTemplate = () => {
+  selectedContentTemplate.value = null;
+};
+
+const onSendMessage = message => {
+  emit('onSend', message);
+};
+
+const onClose = () => {
+  emit('cancel');
+};
+</script>
+
+<template>
+  <woot-modal v-model:show="localShow" :on-close="onClose" size="modal-big">
+    <woot-modal-header
+      :header-title="$t('CONTENT_TEMPLATES.MODAL.TITLE')"
+      :header-content="modalHeaderContent"
+    />
+    <div class="px-8 py-6 row">
+      <TemplatesPicker
+        v-if="!selectedContentTemplate"
+        :inbox-id="inboxId"
+        @on-select="pickTemplate"
+      />
+      <TemplateParser
+        v-else
+        :template="selectedContentTemplate"
+        @reset-template="onResetTemplate"
+        @send-message="onSendMessage"
+      >
+        <template #actions="{ sendMessage, resetTemplate, disabled }">
+          <div class="flex gap-2 mt-6">
+            <Button
+              :label="t('CONTENT_TEMPLATES.PARSER.GO_BACK_LABEL')"
+              color="slate"
+              variant="faded"
+              class="flex-1"
+              @click="resetTemplate"
+            />
+            <Button
+              :label="t('CONTENT_TEMPLATES.PARSER.SEND_MESSAGE_LABEL')"
+              class="flex-1"
+              :disabled="disabled"
+              @click="sendMessage"
+            />
+          </div>
+        </template>
+      </TemplateParser>
+    </div>
+  </woot-modal>
+</template>