test: add edge case tests for LessThan mutations

[deviantintegral]

Add comprehensive tests for boundary conditions identified in mutation testing:

1. HarFileRepository:

   • Test filtering of files with exactly 4 characters
   • Verify files < 4 chars are filtered out
   • Verify .har files >= 4 chars are included

2. Timings:

   • Test setConnect allows connect equal to SSL time
   • Test setConnect throws exception when connect < SSL
   • Test setSend/setWait/setReceive allow zero values
   • Test setSend/setWait/setReceive reject negative values

These tests kill the LessThan mutations identified in the report by:

• Testing the boundary value where < becomes <=
• Ensuring edge cases are properly handled