feat: implement dynamic fee tiers based on pool volume

[EDOHWARES]

Dynamic Fee Tiers Based on Volume

Branch: feature/dynamic-fee-tiers
Issue Reference: #317

Description

This PR implements a dynamic protocol fee system where the fee percentage applied to a pool is determined by its total volume (total stake) at the point of resolution. This incentivizes higher participation by offering lower fee tiers for high-volume markets.

Key Changes

• Data Models:
  • Added FeeTier struct to define stake_threshold and fee_bps.
  • Updated Pool struct to store the resulting fee_bps determined at resolution time.
  • Added DataKey::FeeTiers for persistent configuration storage.
• Dynamic Resolution Logic:
  • Updated resolve_pool, resolve_pool_from_price, and oracle_resolve to calculate and store the applicable fee tier.
  • Added internal helper calculate_dynamic_fee to find the highest threshold tier satisfied by the pool volume.
• Admin Functions:
  • set_fee_tiers: Allows governance to update the fee schedule.
  • get_fee_tiers: Public view function to check active tiers.

Closes #317

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[EDOHWARES]

@Yunusabdul38 , pls review