Adds SketchEngine::make_bridge (4-pole cubic Bezier, G1-tangent to Line/Arc
endpoints, straight-line fallback for other types) emitted as the existing
BSpline SketchEntity — no new geometry type, no serialized-field change, golden
recipe fixture untouched. CadDocument::add_bridge appends it (non-parametric,
index-validated, throws on bad refs). MCP `bridge` method mirrors action_project.
4 new [CadDocument][bridge] tests; full kernel suite green (76 cases, 1280 asserts).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BVzKmX6Y1aEteit1HTXG4Q