Goal: anchoring or setting of joints to known 3D (time series) or fixed points.

• Deliverables: configuration/API for anchors; model integration; missing-data handling if needed.
• Success criteria: anchoring works without breaking shapes/gradients.
• Dependencies: may depend on P1 (if anchors can use Anipose-derived 3D), but can often be developed in parallel once P0 is done.