solidcraft-smlib: the fork at bf7c272, whose operation results hold their own gaps

SMLib's tolerance update now fixes the vertex gaps its check reports (gaps over half a vertex's
tolerance), and every boolean, blend, shell, offset and sweep result grows its vertex and edge
tolerances over gaps below SMLib's own rounding bound before it is handed out. A thread's groove
cut from a shaft no longer fails SMLib's check on vertex gaps of about 1e-5 mm, and an offset
sphere face no longer fails it on an edge gap of 5.015e-6 against 5e-6 (shell/2939).

Also carries the fork's blend commits since ca2559f (second offset per edge, two-setback
chamfers, variable radius laws with a corner refused) and the IGES knot check.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

crates/smlib/SMLIB_REV

@@ -1 +1 @@
-ca2559f785a662c9ec589aa2cdcfaf3217597db8
+bf7c272dd60ec079bdc99f29005d993bd61a042b