fix: part-named export files and tighter STL tessellation tolerances

[Copilot]

Exported STEP/STL files were named with opaque numeric indices (step-b11-Normal-5col-0.zip) instead of part numbers, and STL meshes had visible artifacts on curved surfaces due to coarse tessellation settings.

Changes

• Part-named filenames: "Resolve part IDs" step now emits both part_ids and part_names outputs (same order). Download loops index into the names array to produce {PART_NUMBER}.zip (e.g. ETZ-B11-LB.zip, ETZ-B11-TC.zip).

  PART_IDS=$(echo "$PART_RESOLUTION" | sed -n '1p')
  PART_NAMES=$(echo "$PART_RESOLUTION" | sed -n '2p')
  echo "part_ids=$PART_IDS" >> $GITHUB_OUTPUT
  echo "part_names=$PART_NAMES" >> $GITHUB_OUTPUT

  IFS=',' read -ra NAMES <<< "$PART_NAMES"
  INDEX=0
  for FID in $FIDS; do
    NAME="${NAMES[$INDEX]}"
    curl ... -o "manufacturing/step/${NAME}.zip"
    INDEX=$((INDEX + 1))
  done

• STL quality: Tightened tessellation tolerances to reduce faceting artifacts on radii:

  • angularTolerance: 0.1 → 0.05
  • chordTolerance: 0.05 → 0.01