fix: Rendering of translations based on the user's locale (#13211)

Previously, translations were generated and resolved purely based on the
account locale. This caused issues in multi-team, multi-region setups
where agents often work in different languages than the account default.

For example, an account might be set to English, while an agent prefers
Spanish. In this setup:
- Translations were always created using the account locale.
- Agents could not view content in their preferred language.
- This did not scale well for global teams.

There was also an issue with locale resolution during rendering, where
the system would incorrectly default to the account locale even when a
more appropriate locale should have been used.

With this update, During rendering, the system first attempts to use the
agent’s locale. If a translation for that locale does not exist, it
falls back to the account locale.


**How to test:**

- Set agent locale to a specific language (e.g., zh_CN) and account
language to en.
  - Translate a message.
- Verify translated content displays correctly for the agent's selected
locale
  - Do the same for another locale for agent.
- With multiple translations on a message (e.g., zh_CN, es, ml), verify
the UI shows the one matching agent's locale
- Change agent locale and verify the displayed translation updates
accordingly

app/javascript/dashboard/modules/conversations/components/MessageContextMenu.vue

@@ -62,6 +62,7 @@ export default {
     ...mapGetters({
       getAccount: 'accounts/getAccount',
       currentAccountId: 'getCurrentAccountId',
+      getUISettings: 'getUISettings',
     }),
     plainTextContent() {
       return this.getPlainText(this.messageContent);
@@ -117,11 +118,13 @@ export default {
       this.$emit('close', e);
     },
     handleTranslate() {
-      const { locale } = this.getAccount(this.currentAccountId);
+      const { locale: accountLocale } = this.getAccount(this.currentAccountId);
+      const agentLocale = this.getUISettings?.locale;
+      const targetLanguage = agentLocale || accountLocale || 'en';
       this.$store.dispatch('translateMessage', {
         conversationId: this.conversationId,
         messageId: this.messageId,
-        targetLanguage: locale || 'en',
+        targetLanguage,
       });
       useTrack(CONVERSATION_EVENTS.TRANSLATE_A_MESSAGE);
       this.handleClose();