Boolean: a point at a boundary curve's end is that end, whatever its parameter (text cuts, #391) (#1195)

A point within the point tolerance of a boundary curve's end is that end in the boolean, whatever its parameter, so text cuts no longer leave unmatched sliver vertices (#391). Robustness goldens re-recorded for seeds 0, 34, 39, 41 and 57 with reasons.

crates/engine/src/cmd/clipboard.rs

@@ -527,6 +527,9 @@ mod tests {
         assert_eq!(def["definition"]["targets"], json!(["Plate (copy)"]), "{def}");
         let st = s.world_state();
         let v = |name: &str| solidcraft_kernel::measure(&st.body(name).unwrap().body).unwrap().volume;
-        assert!((v("Plate") - v("Plate (copy)")).abs() < 1e-6, "each plate carries one spring: {} vs {}", v("Plate"), v("Plate (copy)"));
+        // A spring on the wrong plate is hundreds of mm³ off. The two plates are measured apart
+        // (one moved 50 mm), which the boolean and the measure each round in their own way:
+        // a few 1e-6 mm³ on 5000.
+        assert!((v("Plate") - v("Plate (copy)")).abs() < 1e-8 * v("Plate"), "each plate carries one spring: {} vs {}", v("Plate"), v("Plate (copy)"));
     }
 }