Optimize code for performance and load times

[Swofty-Developments]

Refactor build and packaging for performance, reducing artifact size and improving build times.

This PR implements targeted optimizations across the build system, dependencies, and Docker configurations. Key changes include enabling Gradle parallelism and caching, reducing artifact sizes by scoping heavy dependencies (e.g., Minestom, Velocity proxy, Netty, Mongo, Tinylog) to compileOnly or specific modules, and optimizing the Docker image with a smaller base and tuned JVM flags.

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[cursor]

Cursor Agent can help with this pull request. Just @cursor in comments and I'll start working on changes in this branch.
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