Repo health: modernize deps, security, tests, docs

[hippi345]

Summary

Modernizes randobotjava (JavaFX treasure-hunt game) for Java 21, Maven, automated CI, and maintainability while preserving gameplay.

Security

• Secrets: No API keys, tokens, or connection strings were found in the repository history on this branch. Nothing to rotate.
• Added SECURITY.md with reporting guidance.
• Replaced .gitignore (removed the blanket *.yml ignore that blocked CI/Dependabot configs).
• Enabled Dependabot for Maven and GitHub Actions.

Dependencies and runtime

• JDK 21 (LTS) via maven.compiler.release.
• JavaFX 21.0.6 (OpenJFX) as Maven dependencies (JavaFX is not bundled in the JDK).
• JUnit 5.11.4 for tests.
• Spotless + Google Java Format (AOSP) for formatting.
• Standard Maven layout: src/main/java, src/test/java; removed hand-maintained META-INF/MANIFEST.MF.

Working code

• Added missing main() → Application.launch.
• Autoplay runs on a background thread and updates the UI via Platform.runLater (avoids freezing the JavaFX thread).
• Empty grid size on the start screen defaults to 5 instead of throwing NumberFormatException.
• Replaced System.exit(69) with Platform.exit() for cleaner JavaFX shutdown.
• Decoupled Game from View via GameBoardListener (enables headless unit tests).
• Standard Java naming (makeMove, getStatus, etc.) and improved Point.hashCode.

Tests and linting

• 5 unit tests (PointTest, GameTest) — offline, no credentials.
• mvn spotless:check in CI.

CI

• GitHub Actions workflow: JDK 21, Spotless check, compile, test on push / pull_request to master.

License

• Added MIT License (Copyright © 2026 Joel Shearon). No prior LICENSE file existed.

README

• Rewritten with features, requirements, setup, run instructions, tests, project structure, and CI/license badges.

General polish

• .editorconfig added.
• Removed dead/IDE-oriented ignore rules; added target/ and standard Java ignores.

Skipped / N/A

• Env vars: Not applicable (local desktop game).
• Cloud SDK migrations: Not applicable.
• GUI automated tests: Not added (would require headed JavaFX/CI display); core logic is covered by unit tests.

Verification (local)

mvn spotless:check
mvn test

Tests run: 5, Failures: 0

Owner actions

None required for secrets. Use JDK 21+ and mvn javafx:run to play locally.