fix(dimension): complete aligned workflow

Preserve association modes, source geometry, and sub-unit formatting.

src/command.rs

@@ -1212,10 +1212,11 @@ pub enum CmdResult {
     CommitEntitiesAndExit(Vec<EntityType>),
     /// Commit an acadrust entity to the document and end the command.
     CommitAndExit(EntityType),
-    /// Commit an object-selected linear dimension and retain its source link.
-    CommitAssociativeDimension {
+    /// Commit a linear/aligned dimension using the drawing's association mode.
+    /// Object-selection workflows may retain their source.
+    CommitDimension {
         entity: EntityType,
-        source: Handle,
+        source: Option<Handle>,
     },
     /// Commit a Model-tab 3D solid: the acadrust entity (for selection /
     /// persistence) plus its B-rep (cached for boolean ops + shaded