fix(makefile): avoid relinking on makefile

[antiyro]

Key Modifications:

1. Avoid Always Running clean in build: Removed $(MAKE) clean from build, so it won't delete and relink files every time.
2. Timestamp Tracking for Artifacts:
   • The SSJ_DIR target only rebuilds if $(SSJ_ZIP) changes.
   • curl only runs if the zip file doesn't exist.
3. Directory creation conditional: The build directory build/ssj is only recreated when necessary.

---

This change is 

[antiyro]

This is a direct answer to @ClementWalter provocations!

[enitrat]

Thank you for your contribution @antiyro