feat: fillet fit option reduces a radius too large for its edges (#388)

* feat(kernel): typed TooLarge refusal and fillet_max search

Blend refusals caused only by the size (larger than the neighbouring faces,
taller than the walls, longer than the next edge, larger than a corner
radius) now return KernelError::TooLarge, displayed as before. fillet_max
finds the largest radius below a request at which the fillet of the edges
works, to three significant digits, by building candidates; it is an explicit
call (up to 16 fillets), not run on every refusal.

A corner edge that doesn't run square to the edge is now reported as such
instead of as a blend larger than the neighbouring faces.

Refs #293

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TWc1smHYwTSVrVc8SNvS44

* feat: fillet fit option reduces a radius too large for its edges

solid.fillet takes fit: exact (the default, as before: a radius too large
for the geometry around the edges is refused) or reduce: the radius is
reduced to the largest that works for all the picked edges (kernel
fillet_max, three significant digits, every candidate built). The feature
stores the requested radius, so it refits on every evaluation; when it
reduces, the feature's warning says so and the command returns
radius_applied. Pattern copies of the fillet use the same rule. The file
format writes fit only when it is reduce.

The Fillet dialog gets a Radius Fit row (Exact / Reduce to Fit, constant
radius) and, when the preview reduced the radius, an Applied Radius line;
editing the feature keeps the choice.

One radius for all edges for now; per-edge radii and taper follow.

Refs #293

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TWc1smHYwTSVrVc8SNvS44

---------

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>
Co-authored-by: bherbruck <brennen.herbruck@gmail.com>

crates/doc/src/tests.rs

@@ -104,8 +104,17 @@ fn set_back_reports_restored_features() {
 #[test]
 fn box_fillet_cut_timeline() {
     let (mut doc, _) = plate_doc();
-    doc.add_feature(FeatureKind::Fillet { edges: vec![Vec3::new(0.0, 0.0, 10.0)], radius: "3".into(), body: None, style: Default::default() }, None)
-        .unwrap();
+    doc.add_feature(
+        FeatureKind::Fillet {
+            edges: vec![Vec3::new(0.0, 0.0, 10.0)],
+            radius: "3".into(),
+            body: None,
+            style: Default::default(),
+            fit: Default::default(),
+        },
+        None,
+    )
+    .unwrap();
     let mut sk = Sketch::new();
     sk.add_circle(Vec2::new(20.0, 15.0), 5.0, None, None).unwrap();
     let s2 = doc.add_feature(FeatureKind::Sketch { plane: PlaneRef::Origin { name: "XY".into() }, sketch: sk }, None).unwrap();
@@ -163,8 +172,17 @@ fn errors_are_reported_not_fatal() {
         None,
     )
     .unwrap();
-    doc.add_feature(FeatureKind::Fillet { edges: vec![Vec3::new(500.0, 0.0, 0.0)], radius: "1".into(), body: None, style: Default::default() }, None)
-        .unwrap();
+    doc.add_feature(
+        FeatureKind::Fillet {
+            edges: vec![Vec3::new(500.0, 0.0, 0.0)],
+            radius: "1".into(),
+            body: None,
+            style: Default::default(),
+            fit: Default::default(),
+        },
+        None,
+    )
+    .unwrap();
     doc.add_feature(
         FeatureKind::Box {
             corner: point_expr(Vec3::ZERO),