ROM profiles and ground-contact invariants for domain-aware ranges

[a-baran-orhan]

Focused split of Workstream 3 from the dance UAT umbrella #91.

Goal

Support domain-aware movement ranges (e.g. ballet turnout / pointe) without weakening the conservative general ROM defaults. Treat tester-supplied angles as hypotheses to verify with qualified sources, implemented as representation profiles or contextual constraints rather than universal safety claims.

Investigate ROM profiles / contact context

• Review hip external rotation for ballet (current ceiling 45°; UAT suggestion ≥60°, up to 90° for a ballet representation).
• Review ankle dorsiflexion by context (~15° non-weight-bearing, up to ~30° weight-bearing).
• Review ballet plantarflexion (current 50°; pointe-oriented ~90–100°).
• Decide between explicit profiles (general, ballet), configurable rig limits, or solver context inferred from active contacts.
• Keep authored-angle validation and IK/contact constraints aligned under any profile.
• Keep representational ceiling vs medical/safety recommendation explicit.
• Avoid sex-based ROM profiles; prefer explicit rig/user configuration.

Ground-contact invariants

• Reproduce the Demi-plié heel lift with ground-lock: feet.
• Decide precedence when authored pose, ROM clamp, and required contact cannot all be satisfied.
• A declared planted sole must stay visibly planted or produce an explicit unresolved-contact diagnostic (never silently lift).
• Add measurable invariants for heel height, toe height, sole orientation, and foot drift during grounded ballet movements.

Acceptance

• General movements retain conservative default behavior.
• A reviewed ballet configuration can represent required turnout/ankle ranges without changing global defaults accidentally.
• Ground-contact failures are observable via diagnostics and tests.
• No docs present these limits as medical advice.

Priority: P1.