Standardize BAG Rewards Tier Multipliers

Background

Holding BAG gives you bonus multipliers that boost your Blast Gold, Blast Point, cashback, and referral rewards. The more BAG you hold, the more rewards you earn. These rates are outlined here: https://docs.decentral.games/promotions/reward-tiers.

Blast Point and Gold multipliers follow the same multipliers as Cashback, but Referral multipliers are different. The Tier 0 Cashback reward is 5% (so 5x is 25%) and the Tier 0 Referral reward is 25% (so 2x is 50%).

Proposal

(1) For all 4 categories, make Tier 0 - Tier 10 range from 1x - 3x in increments of 0.2. (2) Set the Tier 0 Cashback reward to 10% (so 3x is 30%) and the Tier 0 Referral reward to 15% (so 3x is 45%).

Rationale

Aligning these rates will be easier to maintain and convey to users. It'll also be more memorable given the new 1:1 mapping between Tier and Multiplier across all 4 categories. Moreover, the 5x spread was reasonable for cashback which was previously capped at 25% but it was pretty extreme for Blast Points and Blast Gold. As a result, it capped how high we could set the Tier 0 rewards (which is what most new users will see) and limited our flexibility to give Points/Gold out elsewhere.

Lastly, this is a relatively small change for Cashback and Referral reward levels. Cashback rates end up 5% higher across the board while Referral rewards end up 5 - 10% lower. The combined cap for both remains 75%.