[FreshTVMax]

Overview

This PR adds a graduated bonding curve to the creator-keys program. Instead of a single exponent applied across the entire supply range, the curve now selects an exponent based on configurable supply milestones, allowing creators to design pricing that starts accessible and becomes steeper at higher supply tiers.

Related Issue

Changes

📈 Graduated Bonding Curve

• [ADD] creator-keys/src/supply_milestones.rs
  • Milestone storage and lookup for per-key graduated curve configuration.
  • configure_graduated_curve(key_id: BytesN<32>, milestones: Vec<(u32, u32)>) callable by the key creator; validates each (supply_threshold, exponent) pair with exponents in the 1–5 range.
  • Panics with CurveAlreadyActive if any sales have started before configuration.
  • Emits a graduated_curve_configured event containing all milestone pairs.
  • Exponent selection helper that returns the base exponent below the first milestone and steps up at each configured threshold based on current supply.

Verification Results

cargo build -p creator-keys
✅ compiles

cargo test -p creator-keys
✅ milestone validation, exponent selection at each tier, and CurveAlreadyActive guard covered

Acceptance Criteria	Status
Correct exponent applied at each supply tier	✅ Exponent resolved from the active milestone for the current supply
Buy at supply below the first milestone uses the base exponent	✅ Base exponent returned when supply is under the first threshold
Exponent steps up correctly at each configured milestone threshold	✅ Selection walks milestones in order and applies the matching exponent
Configuration after sales have started panics with CurveAlreadyActive	✅ Guarded before any milestone state is written
graduated_curve_configured event emitted with all pairs	✅ Event includes every configured (supply_threshold, exponent) pair

Closes #829