Fix incomplete clean target in 02/Makefile

[legends1307]

Problem

The clean target in 02/Makefile is incomplete and has two issues:

1. Missing executable removal: The target removes intermediate files (*. o, *.s, *. dump) but doesn't remove the final executable 02.main that is built by the all target
2. No error handling: Uses rm without the -f flag, which will cause errors if files don't exist

Solution

This PR fixes both issues:

• Adds 02.main to the list of files to be removed
• Adds the -f flag to rm to prevent errors when files are missing

[namanlp]

I am closing this since it is stale