Implement Stellar-based Payment System

[SimpleX-T]

Priority: High
Labels: enhancement, stellar, payments, lumens

Description: Replace traditional payment processing with Stellar blockchain transactions using XLM and asset tokens.

Acceptance Criteria:

• Create payment processing service using Stellar transactions
• Support XLM (Lumens) as primary payment method
• Implement payment verification through blockchain confirmation
• Add support for USDC on Stellar for stable pricing
• Create payment escrow system using Stellar multisig accounts
• Implement refund mechanism via blockchain transactions
• Add transaction history tracking from Stellar ledger
• Handle payment failures and retry logic

Technical Implementation:

• Use Stellar's payment operations for direct transfers
• Implement time-bound transactions for booking expiration
• Create payment channels for frequent travelers
• Integrate with Stellar's memo field for booking reference