feat(meanderaw): ✨ drop the degenerate one-strand parallel combinations

[JimmyPaolini]

Parent

#663

What to build

The redundant one-strand parallel combinations are dropped from the swept enumeration. With
both border rules full, aligned-strands-1, plied-strands-1, serpentine-strands-1, and
serpentine-strands-1-flip-one render byte-identically — 33 drawings across eleven row counts
that are four names for one file. At one strand there is nothing to ply and nothing to
serpentine, so aligned-strands-1 is the only honest name.

Acceptance criteria

• plied-strands-1, serpentine-strands-1, and serpentine-strands-1-flip-one are no
  longer produced by the drawing enumeration
• aligned-strands-1 is still produced at every row count
• The 33 redundant committed drawings are removed
• The enumeration's own tests assert the exclusion rather than merely reflecting it, so a
  future strand count cannot silently reintroduce a duplicate

Blocked by

• feat(meanderaw): ✨ draw both border rules in the parallel family #668 — the four are only identical once both border rules are drawn.