Add Manual Bank Transfer Payment (Iran) + EN/FA Translations

[amirsaam]

This PR adds two major features:

1. Manual Bank Transfer Payment Method

• A new payment gateway that allows users to pay via bank transfer when internet-based payments are restricted:
• New MANUAL_TRANSFER gateway type with configurable bank details (bank name, account holder, account number, card number)
• Receipt submission flow — users see bank info and send payment proof (photo/document)
• Admin confirmation system — forwards receipts to admins with inline confirm/reject buttons
• Redis-backed pending state to track unconfirmed payments
• Fully integrated into the existing subscription dialog without affecting other gateways

2. English & Persian (Farsi) Translations

• Added complete English translation files (previously Russian-only)
• Added complete Persian (Farsi) translation files
• Changed default locale from Russian to English

Notes

• This PR was written heavily with AI assistance
• It has not been tested due to Iran's nationwide internet blackout preventing me from running the bot or accessing external services
• Code syntax has been validated with python3 -m py_compile
• All existing functionality is preserved — the manual transfer flow is additive and non-intrusive to existing payment methods
• Persian translations use formal language suitable for a service context

[amirsaam]

Closes #31