Migrate PhysicsLayout with open-source-library-migration guide

[theJawnnybot]

Summary

Applied open-source-library-migration.md to PhysicsLayout.

Build/toolchain

• Java 17
• Gradle 9.3.1 (wrapper + scripts refreshed)
• AGP 9.1.0
• Updated dependency versions to current stable where safe

Publishing

• Maven Central publishing via com.vanniktech.maven.publish
• Switched host to publishToMavenCentral(SonatypeHost.CENTRAL_PORTAL)
• Signing retained for release workflow
• Patch bump in gradle.properties to VERSION_NAME=3.0.3

CI/CD

• Modernized CI workflow + wrapper validation (gradle/actions/wrapper-validation@v4)
• Updated release workflow to:
  • use MAVEN_CENTRAL_USERNAME / MAVEN_CENTRAL_PASSWORD
  • use tag-based version override (no file mutation):
    • -PVERSION_NAME="${GITHUB_REF_NAME}"

Repo/docs cleanup

• Removed JitPack repo from dependency resolution management
• Updated README badges/links to GitHub Actions + Maven Central
• Updated badge asset branch link from master -> main
• Updated library manifest to use namespace approach (<manifest />)

Sample app compatibility

• Removed JitPack-only gimbal dependency from sample app
• Updated AboutActivity gravity handling to use raw gravity sensor values directly
• Added Java 17 compile options and AGP9-compatible proguard defaults

Validation

• ./gradlew build ✅