feat: add response speed tracking in reward calculation

[0xsatoshi99]

Summary

Implements issue #35 - Consider response speed in reward calculation.

This PR adds response latency tracking and applies speed-based multipliers to miner rewards, encouraging miners to optimize their code for the shortest latency.

Changes

New File: game/validator/response_speed.py

• ResponseMetrics: Dataclass tracking per-miner response times, timeout counts, and query totals
• GameResponseTracker: Manages metrics for all miners throughout a game session
• Speed multiplier calculation: Calculates bonus/penalty based on average response time
• apply_speed_multipliers(): Applies speed adjustments to base rewards

Modified: game/validator/forward.py

• Initialize GameResponseTracker at game start
• Record response times for each miner query (including timeouts)
• Apply speed multipliers to final rewards before storing
• Log response speed summary at game end

Speed Multiplier Logic

Response Time	Multiplier
< 5 seconds	Up to +30% bonus
5-20 seconds	No adjustment (1.0x)
> 20 seconds	Up to -20% penalty
>50% timeout rate	Maximum penalty (-20%)

Example Output

📊 Response Speed Summary:
  UID 42: avg=3.21s, fastest=2.15s, timeouts=0/4, multiplier=1.21x
  UID 87: avg=18.45s, fastest=12.30s, timeouts=1/4, multiplier=0.95x

Benefits

• Incentivizes miners to optimize inference speed
• Penalizes unreliable miners with frequent timeouts
• Rewards consistent, fast responders
• Transparent logging for debugging

Fixes #35

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Contribution by Gittensor, learn more at https://gittensor.io/

[0xsatoshi99]

@ultrashiny Can you please check this PR and let me know your opinion?