[WIP] Implement UDP transmitter and receiver for IPacket interfaces

[Copilot]

Thanks for assigning this issue to me. I'm starting to work on it and will keep this PR's description up to date as I form a plan and make progress.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>UDP: transmitter + receiver</issue_title>
<issue_description>## Problem

The actual UDP transport plumbing - implementing the IPacketTransmitter and IPacketReceiver interfaces for UDP.

Sub-tasks

• UdpTransportReceiver implementing IPacketReceiver - accept raw IP packets, extract UDP datagrams, demux by port
• UdpTransportTransmitter implementing IPacketTransmitter - accept datagrams, construct IP+UDP frame, hand to network layer
• Port binding / socket table for demuxing incoming datagrams

Dependencies

Depends on: #105, #106
Unlocks: #108 (UDP delegate chain integration)

Phase

Phase 1 (Core Protocol & Tooling)</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes UDP: transmitter + receiver #107

---

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.