fix: fillet fit review follow-ups (#404)

* fix: fillet fit review follow-ups

From the review of #388 (merged before these landed):
- The Fillet dialog's Applied Radius showed nothing when editing a fillet
  that was already reduced: the preview found the radius by diffing the
  states before and after. The engine's preview now keeps the command
  replies, and the dialog reads the radius of the feature they name.
- Pattern copies of a reduced fillet try the radius the original was
  reduced to first, instead of each searching again (up to 16 fillets).
- fit: reduce with a chord or variable radius is refused instead of being
  silently ignored.
- One helper appends a note to a feature's warning; too_large is imported
  like unsupported in the loop and curve blends.

Refs #293

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

* Use the solidcraft_doc crate name after the rename

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HWLPLy7ug7URSK5WybjRNa

---------

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

crates/engine/src/cmd/features.rs

@@ -790,6 +790,9 @@ fn fillet(s: &mut Session, p: &Value) -> Result<Value> {
         Some("reduce") => solidcraft_doc::FilletFit::Reduce,
         Some(o) => return Err(bad(cmd, format!("unknown fit `{o}` (exact or reduce)"))),
     };
+    if fit == solidcraft_doc::FilletFit::Reduce && !style.is_constant() {
+        return Err(bad(cmd, "`fit: reduce` takes a constant radius"));
+    }
     let mut out = add_feature(s, p, FeatureKind::Fillet { edges, radius, body: str_(p, "body").map(str::to_string), style, fit })?;
     // The radius the fillet used, when `fit: reduce` reduced it.
     if let Some(id) = out.get("feature").and_then(Value::as_u64)