Feat/arabic language support (#13516)

### What problem does this PR solve?

This PR implements comprehensive Arabic language support for the RAGFlow
application. The changes include:
- Complete Arabic translation of all UI text elements in the web
interface
- RTL (right-to-left) layout support for Arabic content
- Localization updates for all supported languages (ar, bg, de, en, es,
fr, id, it, ja, pt-br, ru, vi, zh-traditional, zh)
- UI component adjustments to properly display Arabic text and support
RTL layout

The implementation ensures that Arabic-speaking users can fully interact
with the application in their native language with proper text rendering
and layout direction.

### Type of change

- [x] New Feature (non-breaking change which adds functionality)

<img width="2866" height="1617" alt="image"
src="https://github.com/user-attachments/assets/f2751b34-1b65-4867-b81d-a1068c17b9b7"
/>

---------

Co-authored-by: Yingfeng <yingfeng.zhang@gmail.com>

web/src/components/message-item/index.module.less

@@ -36,7 +36,7 @@
     word-break: break-word;
     :global(section.think) {
       color: rgb(166, 166, 166);
-      border-left-color: rgb(78, 78, 86);
+      border-inline-start-color: rgb(78, 78, 86);
     }
   }
 
@@ -57,9 +57,9 @@
 }
 
 .messageItemLeft {
-  text-align: left;
+  text-align: start;
 }
 
 .messageItemRight {
-  text-align: right;
+  text-align: end;
 }