wip: cave planner route support fixed (L134 design 3); clearance at edge joints open

Arrival edge floor aligned to the passage mouth, 0.75 m backbone floor-support budget, anchors on the planned floor:
0 unsupported, 0 grade failures. Open: 196/50,967 capsule samples blocked where a higher descending edge's floor
backing meets the next edge (route-edge-6/7).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016dhxM43dnWvUu2B5Ph1iG1

Standalone/Research/WorldAssemblerM3/Linux134/layout-seed0-final-gate.json

@@ -0,0 +1 @@
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