fix(trim): arc-arc intersections tested against wrong circle (#370)

cc_angles returns angles on the TARGET circle, but the arc-boundary arm
of arc_seg_ts filtered them against the BOUNDARY arc's angular span —
wrong circle, so arc×arc (and circle×arc, EXTEND-to-arc, bulge-polyline
segment) intersections were dropped and TRIM neither highlighted nor
cut. Re-express the intersection point as an angle on the boundary
circle before the span test, matching line_seg_ts/ellipse_seg_ts.

Co-Authored-By: Claude Fable 5 <[email protected]>

src/modules/draw/modify/trim.rs

@@ -543,7 +543,14 @@ fn arc_seg_ts(
                 }
                 cc_angles(cx, cy, r, *cx2, *cy2, *r2)
                     .into_iter()
-                    .filter(|&a| in_arc(a, *a02, *a12))
+                    .filter(|&a| {
+                        // `a` lies on the TARGET circle — re-express the
+                        // intersection point as an angle on the BOUNDARY
+                        // circle before testing that arc's span (#370).
+                        let px = cx + r * a.cos();
+                        let py = cy + r * a.sin();
+                        in_arc((py - cy2).atan2(px - cx2), *a02, *a12)
+                    })
                     .collect()
             }
             Geo::Circle {