Feature rtl support (#13118)

### What problem does this PR solve?

This PR adds comprehensive **Right-to-Left (RTL) language support**,
primarily targeting Arabic and other RTL scripts (Hebrew, Persian, Urdu,
etc.).

Previously, RTL content had multiple rendering issues:

- Incorrect sentence splitting for Arabic punctuation in citation logic
- Misaligned text in chat messages and markdown components  
- Improper positioning of blockquotes and “think” sections  
- Incorrect table alignment  
- Citation placement ambiguity in RTL prompts  
- UI layout inconsistencies when mixing LTR and RTL text  

This PR introduces backend and frontend improvements to properly detect,
render, and style RTL content while preserving existing LTR behavior.

#### Backend
- Updated sentence boundary regex in `rag/nlp/search.py` to include
Arabic punctuation:
  - `،` (comma)
  - `؛` (semicolon)
  - `؟` (question mark)
  - `۔` (Arabic full stop)
- Ensures citation insertion works correctly in RTL sentences.
- Updated citation prompt instructions to clarify citation placement
rules for RTL languages.

#### Frontend
- Introduced a new utility: `text-direction.ts`
  - Detects text direction based on Unicode ranges.
  - Supports Arabic, Hebrew, Syriac, Thaana, and related scripts.
  - Provides `getDirAttribute()` for automatic `dir` assignment.

- Applied dynamic `dir` attributes across:
  - Markdown rendering
  - Chat messages
  - Search results
  - Tables
  - Hover cards and reference popovers

- Added proper RTL styling in LESS:
  - Text alignment adjustments
  - Blockquote border flipping
  - Section indentation correction
  - Table direction switching
  - Use of `<bdi>` for figure labels to prevent bidirectional conflicts

#### DevOps / Environment
- Added Windows backend launch script with retry handling.
- Updated dependency metadata.
- Adjusted development-only React debugging behavior.

---

### Type of change

- [x] Bug Fix (non-breaking change which fixes RTL rendering and
citation issues)
- [x] New Feature (non-breaking change which adds RTL detection and
dynamic direction handling)

---------

Co-authored-by: 6ba3i <isbaaoui09@gmail.com>
Co-authored-by: Ahmad Intisar <ahmadintisar@Ahmads-MacBook-M4-Pro.local>
Co-authored-by: Ahmad Intisar <168020872+ahmadintisar@users.noreply.github.com>
Co-authored-by: Liu An <asiro@qq.com>

common/settings.py

@@ -244,7 +244,7 @@ def init_settings():
     OAUTH_CONFIG = get_base_config("oauth", {})
 
     global DOC_ENGINE, DOC_ENGINE_INFINITY, DOC_ENGINE_OCEANBASE, docStoreConn, ES, OB, OS, INFINITY
-    DOC_ENGINE = os.environ.get("DOC_ENGINE", "elasticsearch")
+    DOC_ENGINE = os.environ.get("DOC_ENGINE", "elasticsearch").strip()
     DOC_ENGINE_INFINITY = (DOC_ENGINE.lower() == "infinity")
     DOC_ENGINE_OCEANBASE = (DOC_ENGINE.lower() == "oceanbase")
     lower_case_doc_engine = DOC_ENGINE.lower()