fix: cast amount to float for LNbits create_invoice API

LNbits create_invoice expects amount as float, not int. Added
explicit float() cast to both DCA distribution and commission
payment invoice creation calls.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

transaction_processor.py

@@ -920,7 +920,7 @@ class LamassuTransactionProcessor:
             }
             new_payment = await create_invoice(
                 wallet_id=target_wallet.id,
-                amount=amount_sats,  # LNBits create_invoice expects sats
+                amount=float(amount_sats),  # LNBits create_invoice expects float
                 internal=True,  # Internal transfer within LNBits
                 memo=memo,
                 extra=extra
@@ -1085,7 +1085,7 @@ class LamassuTransactionProcessor:
             
             commission_payment = await create_invoice(
                 wallet_id=admin_config.commission_wallet_id,
-                amount=commission_amount_sats,
+                amount=float(commission_amount_sats),  # LNbits create_invoice expects float
                 internal=True,
                 memo=commission_memo,
                 extra={