Resolve issues 487 492

[dorismaduegbunam]

This PR consolidates the resolutions for issues #586, #588, #589, and #590:

1. Unit tests for sell event proceeds matching the sell-path formula output (#586)

• Implements test coverage verifying that sell event proceeds match the independently computed sell-path formula output.
• Checks sell proceeds at supply steps 5 and 10, confirming they are always less than the raw sell price.
  closes Add unit tests for sell event fields matching the sell-path formula output #586

2. Integration test for multi-buyer scenario confirming independent holder balances (#588)

• Verifies that two different wallets purchasing keys for the same creator have their balances tracked independently.
• Confirms that Wallet A buying 3 keys and Wallet B buying 2 keys leaves both wallet balances correct (3 and 2) and Creator supply at 5.
  closes Add integration test for multi-buyer scenario confirming independent holder balances #588

3. Structured log event for admin fee bps update (#589)

• Defines a new structured FeeConfigUpdatedEvent in the contract events module.
• Emits this event inside set_fee_config with the fields old_bps, new_bps, and updated_at_ledger to support off-chain monitors and indexers.
• Adds integration tests asserting the event structure and field values.
  closes Add structured log event for admin fee bps update #589

4. Reference docs for the bonding curve formula and off-chain price prediction (#590)

• Adds a document outlining the bonding curve Flat, Linear, and Quadratic price calculation formulas.
• Documents all constants, worked step-by-step example for supply 0 -> 1, precision/rounding rules, and includes a TypeScript prediction snippet.
  closes Add docs for how the bonding curve formula is derived and how to predict prices off-chain #590

[drips-wave]

@dorismaduegbunam Great news! 🎉 Based on an automated assessment of this PR, the linked Wave issue(s) no longer count against your application limits.

You can now already apply to more issues while waiting for a review of this PR. Keep up the great work! 🚀

Learn more about application limits