Holes on round faces from the app, and Flip for holes at sketch points (#980)

* Holes on round faces from the app, one hole per pick, and Flip for holes at sketch points (#967)

The Hole dialog takes any face: a hole on a round face drills against the face's normal where it
was picked, and its arrow shows that. A round face split at its seam is picked whole, but makes
one hole where it was clicked. Holes at sketch points get Flip (saved as flip in the hole's points,
under format 18), in the command and in the dialog.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* Holes at sketch points show their arrow: into the part, or away with Flip (#967)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

crates/doc/src/document.rs

@@ -1131,6 +1131,9 @@ pub struct MeshData {
 pub struct SketchPoints {
     pub sketch: u64,
     pub ids: Vec<String>,
+    /// Drill the other way: away from the side the holes would go into by themselves.
+    #[serde(default, skip_serializing_if = "std::ops::Not::not")]
+    pub flip: bool,
 }
 
 /// A component: a node of the design tree that owns sketches, features and bodies. The root