Fix: Username generation, RTL button layout, and Cron file paths

[poryajp]

Hello,

I have submitted a few fixes and improvements in this Pull Request:

1. Username Generation Fix (src/includes/functions.php)

• Changed the username generation logic to use the User's Chat ID followed by 2 random digits (e.g., 123456789_45). This makes usernames more identifiable.

2. RTL Display Fix for Buttons (src/includes/functions.php & src/bot.php)

• Swapped the position of "Price" and "Volume" in the inline keyboard buttons.
• This fixes the RTL rendering issue in Telegram where the currency ("تومان") was appearing at the wrong side.

3. Cron Job Path Fix (src/cron.php)

• Fixed the require_once paths. The script was trying to load API files from the includes/ directory instead of the correct api/ directory, causing a "PHP Fatal error".

Please review and merge.
Thanks!