Expand upon our API to improve ease-of-use for third-party addons.

[creatorfromhell]

Type of Change

Please select the type of change this PR represents:

• feat – New feature
• fix – Bug fix
• hotfix – Urgent production fix
• refactor – Code improvement (no behavior change)
• docs – Documentation/config comment changes only
• chore – Build/tooling/internal maintenance
• breaking – Breaking change (requires migration)

If this is a breaking change, clearly describe the migration steps below.

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General Contribution Checklist

• I have read and understood the CONTRIBUTING.md.
• My branch name follows the naming conventions in CONTRIBUTING.md.
• I have signed the Contributor License Agreement (CLA), if required.
• My changes are based on the latest hikari branch.
• I have tested my changes locally.
• Existing functionality has not been unintentionally broken.

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Description of Changes

Clearly explain:

• What was changed?
• Why was it changed?
• What issue does it solve?
• Is this user-facing, developer-facing, or internal?

Example:

This PR fixes incorrect tax calculation when show: false caused balance overflow checks to misbehave.

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Configuration Changes (if applicable)

If this PR modifies config.yml or another configuration file or adds new configuration options:

• All new config entries follow CONFIG-STYLE.md.
• Comments follow the required structure:
  • Plain-English purpose
  • Behavior details (if needed)
  • Advanced notes (if applicable)
  • Warnings (if applicable)
• Section placement follows the defined ordering rules.
• Defaults favor safety and stability.
• Risky settings include WARNING: comments and mitigation guidance.
• Deprecated keys (if any) are clearly marked and documented.
• No existing config defaults were changed unintentionally.

If config changes were made, explain them:

Example:
Added shop.async-price-validation
- Default: false
- Purpose: Improves responsiveness on large servers
- Risk: May increase async task load

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Migration Notes (Required for breaking changes)

If this PR includes a breaking change:

• What changed?
• Who is affected?
• Required admin action?
• Is there automatic migration?

Example:

- shop.display-type=1 is no longer supported.
- Servers must switch to display-type=2.
- No automatic migration is performed.

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Related Issues / References

• Fixes: #___
• Relates to: #___
• Documentation PR: #___

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Testing Notes

How was this tested?

• Local test server
• Networked proxy setup
• With database (MySQL)
• With H2
• Other integrations (describe below)

Additional notes:

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Changelog Entry

If this change is user-facing, provide a changelog entry, which also includes your name/online alias:

### Fix
- Corrected progressive tax bracket calculation edge case.(creatorfromhell)

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Maintainer Review Checklist (Internal)

• Code structure meets project standards
• No unintended side effects
• Config additions follow style guide
• Documentation updated (if needed)
• Changelog entry added
• Breaking change properly labeled

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