Geometry mirror (line systems) — mirror_order, mirror_reflect

Replicates a line scene’s segments under N-fold rotational symmetry to build a true geometric fractal. mirror_order is the fold count (rounds, clamped to 1..=24; 1 = no mirror). mirror_reflect >= 0.5 adds a reflected copy per sector (dihedral). Distinct from the screen-space kaleido_* below: this folds the geometry, that folds the finished pixels. High order on a dense curve is capped at the segment limit and the drop is always surfaced — never a silent cut. A structural overflow (an L-system depth) is reported when the preset loads; a live one, where a bound expression drives mirror_order past the cap while the scene runs, is reported on stderr once when it starts and once when it clears.