Kernel rig: #616's lid shells open at a rib's side, with the 0.15 lip

SMLib keeps the skirt top's offset where its loops wind the other way under the opening, the
cavity's floor (the owner's ruling of 2026-10-31: build it; a lip thinner than the wall is no
break-through).

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

tests/kernel-cases/shell/KNOWN_FAILING

@@ -4,5 +4,4 @@
 # Baseline: 45f69c0e5 with SMLib 60b1c6a, aarch64 Linux.
 316-shell-open-beside-a-bottom-round-r2-4-as-large-as-the-wall-refused builds a shell where the rim has no thickness instead of refusing it
 316-shell-open-beside-a-bottom-round-r2-as-large-as-the-wall-refused builds a shell where the rim has no thickness instead of refusing it
-616-shell-open-a-rib-side-face-of-a-lid SMLib status 1001
 cov-shell-again-open-at-an-inner-wall-of-a-shelled-box SMLib status 1001