Reference tests: the eight cases that fail on SMLib eaa998a name their cause as known failures

Develop 38fd4a4f6's Reference tests fail 34, 35, 77, 78 and 81 (STEP export finds fillet edges
4.6e-5 to 6.1e-5 off their surfaces against 2e-5), 37 (the apex blend 0.193 off), 80 (the
taper-to-fit area) and 83 (thicken status 1001). Each expected.json names its cause in
known_failure, which the oracle already reads: a known failure that passes fails the job.

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

tests/oracle/34-chamfer-then-fillet/expected.json

@@ -1,5 +1,6 @@
 {
   "source": "freecad 1.1.4",
+  "known_failure": "SMLib fillet: STEP export finds edges 4.6e-5 to 6.1e-5 off their surfaces against 2e-5",
   "method": "FreeCAD (OpenCASCADE) build of recipe.json by tools/freecad-oracle/build.py: Part extrude, Part makeChamfer, Part makeFillet",
   "body_count": 1,
   "volume_mm3": 22892.42132988775,

tests/oracle/35-fillet-curved-curved/expected.json

@@ -1,5 +1,6 @@
 {
   "source": "freecad 1.1.4",
+  "known_failure": "SMLib fillet: STEP export finds edges 4.6e-5 to 6.1e-5 off their surfaces against 2e-5",
   "method": "FreeCAD (OpenCASCADE) build of recipe.json by tools/freecad-oracle/build.py: Part extrude, Part extrude join, Part makeFillet",
   "body_count": 1,
   "volume_mm3": 63171.61517720092,

tests/oracle/37-pyramid-apex-blend/expected.json

@@ -1,5 +1,6 @@
 {
   "source": "freecad 1.1.4",
+  "known_failure": "the apex blend's shape is 0.193 mm off the reference (at most 0.05)",
   "method": "FreeCAD (OpenCASCADE) build of recipe.json by tools/freecad-oracle/build.py: Part.makeLoft, Part makeFillet",
   "body_count": 1,
   "volume_mm3": 15465.577113384288,

tests/oracle/77-fillet-variable-linear/expected.json

@@ -1,5 +1,6 @@
 {
   "source": "analytic",
+  "known_failure": "SMLib variable fillet: STEP export finds edges 4.6e-5 to 6.1e-5 off their surfaces against 2e-5",
   "method": "box 40x30x20 with its top front edge (y=0, z=20) rounded at a radius running straight from 2 (x=0) to 5 (x=40): sections are quarter rounds, V = abc - (1 - pi/4) L (a^2 + ab + b^2) / 3; moments and the round's area integrated along the edge (tools/oracle-analytic/cases_fillets.py)",
   "body_count": 1,
   "volume_mm3": 23888.407044966672,

tests/oracle/78-fillet-variable-to-zero/expected.json

@@ -1,5 +1,6 @@
 {
   "source": "analytic",
+  "known_failure": "SMLib variable fillet: STEP export finds edges 4.6e-5 to 6.1e-5 off their surfaces against 2e-5",
   "method": "as 77 with the radius running from 4 (x=0) down to 0 (x=40), where the round closes to the corner: V = abc - (1 - pi/4) L a^2 / 3; the round is three-sided and the corner at x=40 stays",
   "body_count": 1,
   "volume_mm3": 23954.21827485812,

tests/oracle/80-fillet-taper-to-fit/expected.json

@@ -1,5 +1,6 @@
 {
   "source": "analytic",
+  "known_failure": "the taper-to-fit round's area is off the reference (the fillet room law)",
   "method": "plate (top 20 -> 2 wide over x 0..40, 15 high) with its top front edge filleted at 3, fit: taper. The radius is the taper law: a clamped cubic B-spline in u = x/40 on 8 equal spans, control radii min(3, 0.9 room) at the Greville abscissae, room = min(20 - 18u, 15) tan 45 deg (top face width, front face height): 3.0000, 3.0000, 3.0000, 3.0000, 3.0000, 3.0000, 3.0000, 3.0000, 3.0000, 2.4750, 1.8000. Sections are quarter rounds; V, moments and areas integrated along the edge",
   "body_count": 1,
   "volume_mm3": 6525.960225143974,

tests/oracle/81-fillet-spline-radius/expected.json

@@ -1,5 +1,6 @@
 {
   "source": "analytic",
+  "known_failure": "SMLib variable fillet: STEP export finds edges 4.6e-5 to 6.1e-5 off their surfaces against 2e-5",
   "method": "box 40x30x20 with its top front edge (y=0, z=20) rounded at a radius that is a clamped cubic B-spline in u = x/40, knots 0,0,0,0,0.25,0.6,1,1,1,1, control radii 2, 5, 1.5, 4, 1, 3 (r(0) = 2, r(40) = 3). Sections are quarter rounds; V, moments and areas integrated along the edge, exactly per knot span",
   "body_count": 1,
   "volume_mm3": 23933.601078437176,

tests/oracle/83-boundary-loop-thicken/expected.json

@@ -1,5 +1,6 @@
 {
   "source": "analytic",
+  "known_failure": "SMLib thicken fails (status 1001)",
   "method": "region = 10 x 10 square + half disc r 5 on its top side: A = 100 + 12.5 pi, centroid by moments (half disc's at 4r / (3 pi) above its diameter); slab of thickness 2 over it (symmetric about z = 0): V = 2A, area = 2A + 2 (30 + 5 pi)",
   "body_count": 1,
   "volume_mm3": 278.53981633974485,