feat(variation): execute localized joint torque offsets

[d-sorgcodexagent]

Summary

• execute deterministic time-windowed commanded shoulder/wrist torque offsets for the double-pendulum swing model
• enforce topological joint loci, canonical RK4-grid duration, strict non-coercive contracts, and fail-closed unsupported source behavior
• retain honest PyQt behavior by hiding contextual-only inputs until locus authoring lands and rejecting unrepresentable imported plans atomically

Verification

• 147 focused localized-contract and bypass regressions
• 1,483 broad shared swing/variation and Rate tests (plus one expected missing-Rust-wheel skip)
• pinned Python 3.12 / MyPy 1.13 cumulative 16-source gate
• Ruff check/format, diff check, conflict scan
• independent exact-head GO review

Stack

Draft child of #4407. Keep #4142 R10.3/R13.3/R13.5 open: this is the first bounded localized torque execution capability; PyQt/React locus authoring, broader localized sources, Rust parity, and complete state/torque archive authority remain open.