New MCP tool `export_3d_cli` wrapping the kicad-cli 3D subcommands. A
`format` enum {step,glb,stl,ply,brep,xao,vrml} selects the subcommand and
the handler forwards only flags valid for that subcommand: the shared
geometry/include set for step/glb/stl/ply/brep/xao, no-optimize-step for
STEP only, and units + models-dir/models-relative for VRML. Rich CLI
sibling of the existing export_3d / export_vrml (left untouched). Reads
the saved .kicad_pcb.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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