fix(contacts): Show telegram id in contact details form (#13611)

## Summary
This change fixes a mismatch in contact details where Telegram data
could be shown in the contact profile/social icon area but was not
available in the editable contact form.

### What changed
- Added Telegram to the social links section of the next-gen contact
form so agents can view and edit it alongside Facebook, Instagram,
TikTok, Twitter, GitHub, and LinkedIn.
- Added Telegram support to the legacy conversation contact edit form
for parity between both contact editing experiences.
- Mapped social_telegram_user_name into the editable socialProfiles
payload when preparing contact form state, so Telegram usernames sourced
from channel attributes are visible in the form.
- Updated the conversation contact social profile merge logic so
Telegram display prefers an explicitly saved social profile value and
falls back to social_telegram_user_name when needed.
- Added the missing English i18n placeholder: Add Telegram.

### Why
Without this, users could see Telegram info in some contact views but
could not reliably edit it in contact details, creating inconsistent
behavior between display and edit states.

---------

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

app/javascript/dashboard/components-next/Contacts/ContactsForm/ContactsForm.vue

@@ -44,6 +44,7 @@ const SOCIAL_CONFIG = {
   LINKEDIN: 'i-ri-linkedin-box-fill',
   FACEBOOK: 'i-ri-facebook-circle-fill',
   INSTAGRAM: 'i-ri-instagram-line',
+  TELEGRAM: 'i-ri-telegram-fill',
   TIKTOK: 'i-ri-tiktok-fill',
   TWITTER: 'i-ri-twitter-x-fill',
   GITHUB: 'i-ri-github-fill',
@@ -66,6 +67,7 @@ const defaultState = {
       facebook: '',
       github: '',
       instagram: '',
+      telegram: '',
       tiktok: '',
       linkedin: '',
       twitter: '',
@@ -103,9 +105,13 @@ const prepareStateBasedOnProps = () => {
     countryCode = '',
     country = '',
     city = '',
+    socialTelegramUserName = '',
     socialProfiles = {},
   } = additionalAttributes || {};
 
+  const telegramUsername =
+    socialProfiles?.telegram || socialTelegramUserName || '';
+
   Object.assign(state, {
     id,
     name,
@@ -119,7 +125,10 @@ const prepareStateBasedOnProps = () => {
       countryCode,
       country,
       city,
-      socialProfiles,
+      socialProfiles: {
+        ...socialProfiles,
+        telegram: telegramUsername,
+      },
     },
   });
 };