Fix Gradle 9.4 compatibility issues

[Robothy]

• Replace io.franzbecker:gradle-lombok plugin (uses removed setMain() API) with a plain JavaExec delombok task using mainClass.set()
• Add junit-platform-launcher to testRuntimeOnly classpath, required by Gradle 9 for JUnit Platform test execution

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.76%. Comparing base (6a6ab8a) to head (57258a3).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##               main     #236   +/-   ##
=========================================
  Coverage     90.76%   90.76%           
  Complexity     1459     1459           
=========================================
  Files           248      248           
  Lines          5325     5325           
  Branches        399      399           
=========================================
  Hits           4833     4833           
  Misses          338      338           
  Partials        154      154           

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