feat: Enhanced Discovery Algorithm (Log-scaling & Time Decay)

[TodouWisiper]

🚀 Enhanced Discovery Algorithm Implementation

This PR optimizes the bounty scoring function to provide a more balanced and relevant ranking system.

🧠 Algorithm Logic:

1. Reward Weight (Logarithmic Scaling): Uses log2 of the reward. This ensures higher-paying bounties get a boost without completely overshadowing high-quality smaller tasks.
2. Funding Confidence: Directly weighs the undedPercent to prioritize guaranteed payouts.
3. Recency Decay: Implements a 30-day linear decay. Freshly posted bounties receive a significant visibility boost to attract early contributors.
4. Engagement Bonus: Rewards tasks with existing claims, indicating community validation and active interest.

📊 Formula:

Score = (log2(Reward) * 5) + (Funding% / 5) + (max(0, 30 - DaysAgo) / 2) + (Claims * 2)

Closes #3