Convert x402 sign command to use positional argument

[jancurn]

Summary

Refactored the x402 sign command to accept the PAYMENT-REQUIRED header as a positional argument instead of a required -r flag, improving the command's usability and consistency with CLI conventions.

Key Changes

• Changed x402 sign command signature from sign -r <base64> to sign <payment-required>
• Converted the -r, --payment-required required option to a positional argument parameter
• Updated the action handler to receive paymentRequired as the first parameter instead of accessing it from opts
• Removed -r and --payment-required from the OPTIONS_WITH_VALUES parser configuration
• Updated test cases to reflect the new positional argument syntax
• Updated CLI help text and documentation to show the new command format

Implementation Details

• The positional argument is now passed directly to the action handler as paymentRequired, eliminating the need for the -r flag
• All other options (--amount, --expiry) remain as optional flags
• Parser validation tests were updated to verify the new syntax works correctly
• The change is documented in CHANGELOG.md as a breaking change in the command interface

https://claude.ai/code/session_018NNkSjHsJrLhG1cAgdmdvY