Verify correctness of offloading algorithm

[ff225]

The offloading decision logic in offloading_algo.py needs a correctness review.

Areas to check:

• The evaluation formula: initial_cost + (layer_data_size / avg_speed) + edge_computation_cost — verify it accurately models end-to-end latency
• Fallback behavior when avg_speed is 0 (currently defaults to 1)
• Whether the valid offloading points filter correctly excludes skip-connection layers in all cases
• Consistency of EMA smoothing across device times (α=0.5), edge times (α=0.5), and per-layer inference times (α=0.2)

Goal: Confirm the algorithm reliably selects the optimal offloading layer under varying network and compute conditions, or identify where it may produce suboptimal decisions.