test(simulation): implement async network impairment proxy with packet loss and jitter simulation

[archittmittal]

Objective & Scope

Implement the network impairment simulation proxy server in tests/simulation/impairment_server.py.

Technical Details & Implementation Plan

• Async HTTP mock server introducing configurable packet loss (0.5% - 10%), RTT latency (50ms - 500ms), jitter, and socket dropouts
• Dynamic impairment profiles (Clean Fiber, Lossy Mobile, High Latency Satellite, Congested Edge)

Deliverable Files

• tests/simulation/impairment_server.py
• tests/simulation/test_impairment.py

Acceptance Criteria & Checkpoints

• Simulation server successfully reproduces dropouts and latency profiles in tests

Parent Epic

Part of Epic #44