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/ui-egui/src/dialogs.rs

@@ -1577,6 +1577,22 @@ pub fn show(app: &mut SolveApp, ctx: &egui::Context) {
                         );
                         enter |= field(ui, radius);
                         ui.end_row();
+                        // A constant radius too large for the edges: refused, or reduced to the
+                        // largest that fits (the preview shows what was used).
+                        if !*chamfer && rtype == 0 {
+                            row_label(ui, "Radius Fit");
+                            let fit = extra_choice(ui, &mut d.extra, "fi_fit", "fit", &[("Exact", "exact"), ("Reduce to Fit", "reduce")]);
+                            ui.end_row();
+                            if fit == 1
+                                && let Some(r) = app.preview.applied
+                            {
+                                row_label(ui, "Applied Radius");
+                                ui.label(RichText::new(crate::prefs::show_mm(app, r, 1)).color(t.warning));
+                                ui.end_row();
+                            }
+                        } else if !*chamfer {
+                            d.extra.remove("fit");
+                        }
                         if *chamfer && *ctype == 1 {
                             row_label(ui, "Distance 2");
                             enter |= field(ui, distance2);
@@ -3303,6 +3319,10 @@ pub fn for_feature(app: &SolveApp, id: u64, marker: Option<usize>) -> Option<Dia
                     *flip = *f;
                 }
             }
+            // A fillet that reduces a radius too large for its edges.
+            if let FeatureKind::Fillet { fit: solvecraft_engine::doc::FilletFit::Reduce, .. } = &f.kind {
+                d.extra.insert("fit".into(), json!("reduce"));
+            }
             // A chord-length or variable fillet.
             if let FeatureKind::Fillet { style, .. } = &f.kind {
                 match style {