governance: Repository license changed from CC-BY-4.0 to AGPL-3.0

[mellanon]

The repository license has been changed from CC-BY-4.0 to AGPL-3.0, effective 2026-02-16.

What changed:

• LICENSE — AGPL-3.0
• CONTRIBUTING.md — Repository license section, DCO, three-layer licensing model
• TRUST-MODEL.md — Added threat vector specflow-lifecycle: Align with @jcfischer on extending SpecFlow bundle #4 (ecosystem extraction)
• CLAUDE.md — Updated license enforcement rules

Commit: 824844f

cc @jcfischer @Steffen025

[Steffen025]

Acknowledged — noted the AGPL-3.0 transition.

Good to see Threat Vector #4 (ecosystem extraction) added to TRUST-MODEL.md — that was exactly the concern we raised in the governance review (PR #101).

One question for clarity: the three-layer licensing model in CONTRIBUTING.md — does this mean standalone tools like pai-review-mode (MIT licensed, registered on the blackboard) are unaffected by the repository license change? i.e., the AGPL-3.0 applies to the pai-collab coordination layer itself, while tools keep their own licenses as declared in PROJECT.yaml?