v0.20.0: full refactor

[shellrow]

Full Refactor (Breaking Changes)

Core Changes

• Overall codebase refactor across all crates for clarity and consistency.
• nex-datalink: Some refactoring for linux
• nex-packet:
  • All protocol packet structures are now fully implemented as strongly-typed structs.
  • Macro-based parsing logic has been eliminated for better transparency and testability.
  • Packet builders are now integrated directly into nex-packet, unifying construction and parsing logic.
• nex-socket:
  • Introduced separate Socket structs for TCP, UDP, and ICMP.
  • All socket types are now async-compatible with tokio.
  • Refactored with clear ownership and connection flow patterns.

Testing and Examples

• Added comprehensive tests and real-world examples