feat(commands): integrate standard CAD commands and fix behavior gaps

Broad pass over the command set: integrate missing commands, wire
previously-unreachable ribbon/menu buttons, and correct name/behaviour
mismatches. Every UI command token now resolves (real handler where the
infrastructure exists, an honest "not yet implemented" status otherwise).

New commands:
- Draw: 3DPOLY, 2D solid (SO/SOLID2D), HELIX, TRACE, SKETCH, DIMCENTER
  (DCE/CENTERMARK)
- Modify/inquiry: REVERSE, MEASUREGEOM (MEA), DBLIST
- Data/manage: BASE, OVERKILL (exact-duplicate removal), AUDIT (read-only
  integrity report), SETVAR (system-variable get/set), SCRIPT (.scr runner),
  FINDNONPURGEABLE

Behaviour fixes:
- LINE and SPLINE gain Close/Undo; AREA computes area/perimeter in f64
  (correct at large coordinates)
- ATTEDIT/ATE unified so the alias and the ribbon button open the
  interactive editor; -ATTEDIT is the command-line form
- Linear/aligned/radius/diameter dimensions gain a text override (Text) and
  text angle (Angle) option
- INSERT gains Scale/Rotate options; COPY gains an Array option
- LINETYPE SET sets the current entity linetype; SETBYLAYER resets overrides
- UNDO accepts a step count

Integrations: standard dimension/block aliases (DLI/DRA/DAN, BMAKE,
EXPORTPDF, DDIM), drafting-aid and screen toggles (GRID/SNAP/POLAR/OSNAP/
DSETTINGS/CLEANSCREEN/QUICKPROPERTIES), viewport tiling
(CASCADE/HORIZONTAL/VERTICAL/VPJOIN), and customization entry points
(CUI/ALIASEDIT).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/app/commands/dim.rs

@@ -17,21 +17,21 @@ impl OpenCADStudio {
                 self.tabs[i].active_cmd = Some(Box::new(cmd));
             }
 
-            "DIMLINEAR" => {
+            "DIMLINEAR" | "DLI" => {
                 use crate::modules::annotate::linear_dim::LinearDimensionCommand;
                 let new_cmd = LinearDimensionCommand::new();
                 self.command_line.push_info(&new_cmd.prompt());
                 self.tabs[i].active_cmd = Some(Box::new(new_cmd));
             }
 
-            "DIMRADIUS" => {
+            "DIMRADIUS" | "DRA" => {
                 use crate::modules::annotate::radius_dim::RadiusDimensionCommand;
                 let new_cmd = RadiusDimensionCommand::new();
                 self.command_line.push_info(&new_cmd.prompt());
                 self.tabs[i].active_cmd = Some(Box::new(new_cmd));
             }
 
-            "DIMANGULAR" => {
+            "DIMANGULAR" | "DAN" => {
                 use crate::modules::annotate::angular_dim::AngularDimensionCommand;
                 let new_cmd = AngularDimensionCommand::new();
                 self.command_line.push_info(&new_cmd.prompt());