Rewrite maifetch in Java 8

[alejandrorivas-pixel]

Closes #1.

/claim #1

This follows the latest maintainer direction in the existing PR comments: rewrite maifetch in Java 8 while preserving the current CLI/config behavior and MaiTea API coverage.

Summary:

• replaced the Go CLI and wrapper with a Java 8 Maven project
• preserved config file, environment variable, and CLI precedence
• supports documented MAITEA_* env vars plus legacy MAIFETCH_* vars
• keeps the profile/recent-score terminal output shape with ANSI colors and optional icon ASCII rendering
• keeps MaiTea wrapper coverage for profiles, tracks, plays, all plays, best scores, all best scores, and status
• added focused tests for config precedence, output formatting, bearer auth, and API JSON parsing
• added a GitHub Actions workflow that runs mvn -B test on Java 8
• updated build docs to mvn package and a runnable shaded jar

Validation:

• mvn test
• mvn package
• java -jar target/maifetch-1.0.0-SNAPSHOT.jar --help
• javap -verbose target/classes/com/github/hutchyben/maifetch/Main.class | rg "major version" -> major version: 52
• git diff --check
• Fork CI passed on this commit: https://github.com/alejandrorivas-pixel/maifetch/actions/runs/27225308385

Payout details can be coordinated privately after acceptance.