Equal: apply each Multiple pick at once, take typed coordinates as picks

Multiple now follows the reference flow: every pick after the first is
made equal right away under `Select object to make equal to first:` and
Enter ends the command with `Length of objects made equal` (or `Radius
…`). A typed coordinate at one of the command's object prompts picks the
object under that point instead of being refused as a point.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

src/command.rs

@@ -1598,6 +1598,9 @@ pub enum CmdResult {
     AddEqualConstraint {
         first: crate::scene::parametric_constraints::ParametricRef,
         others: Vec<crate::scene::parametric_constraints::ParametricRef>,
+        /// A Multiple flow: the command stays for more picks; an empty
+        /// `others` is its Enter and prints the summary line.
+        multiple: bool,
         label: &'static str,
     },
     /// Adds a point or object symmetry relation around a picked line. The
@@ -2438,6 +2441,11 @@ pub trait CadCommand: Send {
         false
     }
 
+    /// Take a typed coordinate at an object prompt as a pick at that point.
+    fn typed_point_picks_entity(&self) -> bool {
+        false
+    }
+
     /// Include filled hatch / DXF SOLID regions in the entity hit-test.
     ///
     /// Most entity-pick commands operate on curve geometry and intentionally