Run rest-pose joint continuity checks even when pose sweep exceeds budget #925

Current develop still skips the rest-pose mechanism.joint-mesh-gap check when the articulated BREP pose sweep exceeds its work budget. A disconnected link can therefore remain unverified while evaluation returns success.

Preserve the useful validation work from #884 separately from its obsolete SO-100 geometry. #913 replaced that geometry with vendor motor meshes and URDF-frame kinematics, so the combined old branch should not be merged.

Source to recover: af2d17bf0dc018c9e6c7137cb6a914c286ab3c8d on cursor/so100-gripper-seat-1c05 (branch retained), especially mechanismTruth.ts, jointMeshContinuity.ts, the BREP distance helpers and their regression tests.

Acceptance:

• A demonstrably disconnected joint fails at rest even with sweepBudget: 0; pose-sweep coverage can still remain unverified.
• Nearby fastened servo geometry or remote fingertip contact must not mask a disconnected link. Reassess the old fixed 32 mm bearing-axis threshold against current models rather than copying it blindly.
• An unavailable measurement reports explicit unknown/failure evidence and cannot claim verified continuity.
• Keep the current Fix the SO-100 arm kinematics and re-capture the landing hero video #913 SO-100 geometry and kinematics; verify connected valid mechanisms and the full regression suite before merging.

The old PR has merge conflicts and several failed CI checks. Its validation changes are not delivered by closing the PR.