Resolve Sonar findings (#279)

[AndreasIgel]

Summary

Fixes the three code-level Sonar findings from #279 (the fork-sonar.yml untrusted-fork hotspot is intentionally left for its own ticket). No behavior changes.

• ProcessorTestUtils.extractTopLevelTypeName — regex with super-linear backtracking (^\s*(?:mod)?(?:\s+(?:mods))*\s* stacks whitespace quantifiers). Now each modifier consumes its own trailing whitespace, ^[ \t]* no longer spans lines, and both patterns in the file are static final Pattern constants instead of being compiled per call:

  (?m)^[ \t]*(?:(?:public|protected|private|abstract|final|static|sealed|non-sealed|strictfp)\s+)*(?:@?interface|class|enum|record)\s+([A-Za-z_]\w*)\b
  

• RoasterCodeGenerator.addParameter — conditional moved inside the operation; one varArgs boolean replaces two instanceof checks:

  boolean varArgs = lastParameter && paramDto.getParameterType() instanceof TypeNameArray;
  TypeName parameterType = varArgs ? ((TypeNameArray) ...).getTypeOfArray() : paramDto.getParameterType();
  method.addParameter(mapType(parameterType), ...);

• ConfigurationProcessingTest.allConfigurationOptions_MustBeSettableViaBuilder — 27 assertions > 25 limit. The builder chain moved into buildFullyConfigured(); the OptionState assertions stay in the original test and the AccessModifier/suffix/formattingMode assertions moved to allConfigurationOptions_AccessNamingAndFormatting_MustBeReadable. No assertion dropped.

Processor module: 420 tests green. Generated example builders unchanged (CI drift check passes).