Refine creator read views and quote helpers

[Ejere]

Summary

This pull request resolves issues #75, #77, #78, and #84 by tightening the contract read paths without changing the underlying trading behavior.

The changes focus on three areas:

• centralizing repeated creator-profile reads used by methods that require a registered creator
• adding an explicit read-only creator supply method with clear error semantics for unregistered creators
• improving quote-view typing and test coverage for existing read methods

What Changed

• Added a shared read_registered_creator_profile helper to consolidate the common pattern of loading a creator profile and returning ContractError::NotRegistered when absent.
• Reused that helper in existing registered-creator read paths and state-changing paths where the same storage lookup behavior was duplicated.
• Added get_creator_supply, a read-only method that returns the current supply for a registered creator and fails cleanly for unknown creators.
• Added a scoped QuoteViewResult type alias for quote-related view helpers so quote return typing is clearer and reusable without changing externally observable behavior.
• Added focused tests for get_creator_fee_recipient, covering successful lookup, repeated read-only access, and the unregistered-creator failure path.
• Added focused tests for get_creator_supply, covering successful reads, read-only behavior, and the unregistered-creator failure path.

Issue Mapping

• Closes Add shared helper for creator config reads #75 by centralizing shared creator-config/profile read behavior.
• Closes Add read-only creator supply method #77 by adding a dedicated read-only creator supply method.
• Closes Add quote view result type alias #78 by introducing a clear shared alias for quote-view result typing.
• Closes Add unit tests for creator treasury share read method #84 by adding unit tests around the creator treasury share read path currently represented by get_creator_fee_recipient.

Behavior Notes

This change is intended to be behavior-neutral aside from the addition of the new get_creator_supply view method.

Existing buy, sell, fee, and quote logic remain unchanged. The helper and alias additions are internal refactors intended to reduce repeated logic and make the read surface easier to maintain.

Testing

• cargo fmt --all
• cargo test --workspace

Closes #75
Closes #77
Closes #78
Closes #84

[drips-wave]

@Ejere 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