fix: correct v2 receipt parsing and trim trailing zeros in confirm dialog

[samarthpatel24]

Summary

• Pass actual x402_version to display_settlement_info instead of hardcoded 1, so v2 receipts are found in
  the correct header
• Trim trailing zeros in --confirm dialog ("0.010000 USDC" → "0.01 USDC")

// receipt fix
-  protocol.parse_receipt_json(response, 1)
+  protocol.parse_receipt_json(response, version)

// trailing zeros fix
-  format!("{whole}.{frac:0>width$} {symbol}", ...)
+  let trimmed = frac_str.trim_end_matches('0');
+  format!("{whole}.{trimmed} {symbol}")

Test plan

• cargo check passes