refactor: ♻️ modernize build system (Kotlin DSL & Version Catalog)

[Nukecraft5419]

🚀 Build System Modernization & Refactoring

This PR focuses on modernizing the project's build infrastructure to improve maintainability, build speed, and developer experience. No functional changes were made to the plugin logic.

🛠 Changes:

• Migrated to Kotlin DSL: Converted build.gradle to build.gradle.kts for better type safety and IDE auto-completion.
• Implemented Gradle Version Catalog: Moved all dependencies and plugin versions to gradle/libs.versions.toml for centralized management.
• Upgraded Gradle Wrapper: Updated to 9.2.1 for performance improvements and compatibility with the latest Java versions.
• Standardized Line Endings: Added a .gitattributes file to ensure consistent line endings (LF for scripts/code, CRLF for batch files) across Windows, Linux, and macOS.
• Optimized Environment: Added standard headers to gradle.properties.

🧹 Clean-up:

• Removed old .gradle artifacts and renormalized the repository line endings.
• Ensured the project is ready for Java 25+ (and compatible with 2026 standards).

✅ Verification:

• ./gradlew clean build runs successfully.
• Tested with IntelliJ IDEA 2025.3