Implement network audit logging for fcctl-core #667

Summary

Implement network audit logging for Firecracker VMs.

Context

PR #426 (feat(rlm): RLM orchestration with MCP tools) requires network audit logging for security and debugging.

Requirements

The implementation should provide:

1. Network interface monitoring and logging
2. Connection tracking
3. Traffic analysis
4. Audit log storage and retrieval

Existing Implementation

terraphim_firecracker/src/vm/network.rs is currently empty and needs implementation.

Related

Blocked by: #664 (Create fcctl-core crate)