GPExpansion

Overview

• Update README and add interactive sign setup wizards
• Add interactive setup wizards for rental, sell, and mailbox signs with /rentclaim, /sellclaim, and /mailbox commands.
• Update README with comprehensive documentation for new wizard system, flexible sign formats (short and condensed), and expanded permissions.
• Add PacketEvents integration for improved sign GUI experience with fallback support. Include new commands /claiminfo and /cancelsetup.
• Add Messages/lang system with /gpx reload support

Full changelog: 0.1.0a...0.1.1a