[Feature Request] Proper signed chat and signed command support (1.19+) #342

InteractiveChat currently relies on forcing unsigned chat and command packets for compatibility with Minecraft's signed-message system.

This can cause compatibility problems with other chat plugins, especially those using Adventure components and custom private-message handling, such as Carbon Chat.

For example, normal chat partially works (in a not recommended way), but InteractiveChat placeholders in /msg do not work correctly.

Requested behavior:

• Preserve the original signed message content and signature wherever technically possible.
• Apply interactive components as unsigned decoration rather than modifying signed content.
• Support signed command arguments, including /msg, /tell, and /w.
• Improve compatibility with third-party chat plugins using Paper's modern Adventure chat API.
• Avoid forcing all chat packets to become unsigned when unnecessary.

Related issues: #314, #217, #335.