feat: add export_pos tool (kicad-cli, full placement-file option set)

New MCP tool `export_pos` wrapping `kicad-cli pcb export pos`: exposes
side, format, units, bottom-negate-X, drill-file origin, SMD-only,
exclude-through-hole, exclude-DNP and gerber-board-edge. Rich CLI sibling
of the existing SWIG-limited export_position_file (left untouched).
Self-contained interface handler reading the saved .kicad_pcb.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/tools/registry.ts

@@ -64,6 +64,7 @@ export const toolCategories: ToolCategory[] = [
       "export_odb",
       "export_ipcd356",
       "export_gencad",
+      "export_pos",
       "export_pdf",
       "export_svg",
       "export_3d",