Function compute_fee_shares

pub fn compute_fee_shares(
    cur_total_assets: Number,
    last_total_assets: Number,
    performance_fee: Wad,
    total_supply: Number,
) -> Number

Computes fee shares to mint given:

• cur_total_assets: current total assets under management
• last_total_assets: previous total assets snapshot
• performance_fee: WAD fraction (1e18 = 100%)
• total_supply: current total share supply

Floors intermediate divisions; returns 0 when no profit, zero fee, zero supply, or when the fee consumes all assets (cur_total_assets == fee_assets).