Set up testing and support iOS 18

[fulldecent]

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[Copilot]

Pull request overview

This PR modernizes the testing infrastructure and updates iOS version support. The changes rename "master" to "main" throughout, document command-line testing procedures, update CI to use newer build environments, and clean up funding links.

Key changes:

• Updated GitHub Actions CI to use macOS 15, Xcode 16.4, and iOS 18.5 simulators
• Added comprehensive testing documentation in README with command-line examples
• Set Example app deployment target to iOS 18.6

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
README.md	Added testing section with command-line build/test instructions, removed tip jar link, updated template reference to swift6
Example/Example.xcodeproj/project.pbxproj	Updated iOS deployment target to 18.6 for both Debug and Release configurations
CHANGELOG.md	Reformatted with consistent markdown headers, updated branch reference from "Master" to "Main"
.github/workflows/test.yml	Upgraded CI to macos-15 runner, Xcode 16.4, and iPhone 16 with iOS 18.5; split build and test into separate steps
.github/FUNDING.yml	Removed Amazon wishlist funding link, kept PayPal

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[Copilot]

The example uses a placeholder UUID XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX which users need to replace. Consider adding a note above or in comments explaining that users should replace this with their actual simulator ID from the previous command.