Reject ambiguous origin and construction plane names (#247)

* Reject ambiguous origin and construction plane names

* Reserve origin plane names for construction planes; suggest the other alias

A construction plane can no longer be created with or renamed to XY, XZ, YZ, Top, Front or
Right, so a plane argument can't become ambiguous in new designs. For older designs that
already hold such a plane, the ambiguity error now also names the origin plane's other
alias (XY for Top...). The existing tests build those legacy names directly.

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

---------

Co-authored-by: bherbruck <brennen.herbruck@gmail.com>
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

ROADMAP.md

@@ -64,6 +64,10 @@ headline counts in-scope tabs only and lists the deferred ones separately.
 
 ## Dimensioning and error reporting
 
+- Construction planes cannot take an origin-plane name (XY, XZ, YZ, Top, Front, Right). Plane
+  arguments reject such a name when an older design's construction plane already has it. Use
+  the other alias, the construction feature's numeric ID or an explicit plane; existing
+  stored references keep their saved meaning. Section Analysis uses the same check.
 - Sketch text can be edited from a selected outline's context menu or the Edit Text command.
   Content, baseline X/Y, height and rotation update the original text source in one undo step;
   cancelling or rejecting an invalid value preserves the sketch. Position and height fields