Relicense from Apache 2.0 to GNU GPLv3

[TGPSKI]

Summary

Relicense skeptic from Apache 2.0 to GNU General Public License v3.0.

Copyleft ensures skeptic remains free and open — anyone who modifies and distributes the scanner must share their changes under the same terms. No proprietary forks, no closed rule packs built on top.

Why GPLv3

• Copyleft protection — modifications must be shared under the same license
• Anti-tivoization — prevents embedding in locked-down appliances that block user modifications
• Stronger patent grant — automatic license termination if a distributor initiates patent litigation
• Alignment — skeptic exists because structural trust boundary violations were invisible to every existing scanner category. The tool should stay permanently available to the people who need it.

What changes

• LICENSE file replaced: Apache 2.0 → GPLv3
• No code changes
• No release required — applies to the repository going forward