Upgrade Custom Core PHP 8.3 B2B Platform to Dynamic Multi-Domain (Single Codebase)

I have an established B2B platform on Custom Core PHP 8.3.
I need an expert developer to unify the architecture into a Single Codebase that dynamically serves two domains (egyptmart.com and arab-mart.com).

Key Requirements:
* Dynamic Routing: Implement a mechanism to detect the incoming domain and serve the corresponding language and configuration using a single set of core files.

* Dynamic Database Mapping: The platform uses parallel tables (e.g., business_profile for Arabic and business_profile_arabyos for English). You must implement dynamic table mapping in the config file to query the correct table based on the active domain.Localization (I18n): Extract all UI strings from pages into dedicated language files (ar.php, en.php).

* Modern CSS Layout: Implement automatic RTL/LTR shifting using CSS Logical Properties (e.g., margin-inline-start, padding-inline).
* Manual hardcoded "page flipping" is strictly prohibited.

* Preservation of Core Logic: Existing functional logic, background scripts, and automation files in the root directory must remain untouched and fully operational
This project is strictly for structural refactoring without altering the existing technical infrastructure.

### Payment & Delivery Agreement
1. Payment release dates are subject to the client's acceptance.
2. Existing files must be preserved not be replaced.
3. Time Deadline: within maximum 5 consecutive calendar days.

Security: I will execute database updates based on your instructions.