Add macosArm64 target and migrate iosMain to appleMain

[solcott]

• Add macosArm64() to the Kotlin Multiplatform targets in KotlinMultiplatformConventionPlugin
• Move Clock.ios.kt from the iosMain directory to appleMain to support the broader Apple platform ecosystem

Closes #733

Description

Adds macosArm64 as a supported KMP target, enabling Store to be used in Compose Multiplatform desktop apps and shared libraries that target macOS. The Clock.ios.kt source file is moved from iosMain to appleMain so the implementation is shared across all Apple targets rather than duplicated.

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Test Plan

Verified the macosArm64 target compiles successfully and existing tests pass locally.

Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my change is effective
• New and existing unit tests pass locally with my changes