annotation: annotative dimstyles ignore DIMSCALE; unit-converted scales

An annotative dimension style still stores a DIMSCALE (100 in ACA
templates), but its features are sized by the annotation scale. Using
the stored value drew 3 mm dimension text 300 units tall, burying the
plan under giant digits.

Some templates also store their ratio scales already converted to the
drawing unit (a metre drawing's "1:50" as 1 paper = 0.05 drawing, with
CANNOSCALEVALUE 20). Applying the INSUNITS conversion on top shrank
the annotation multiplier a thousandfold.

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

src/entities/dimension.rs

@@ -1756,6 +1756,12 @@ pub(crate) fn resolved_dimension_style(
         }
     }
 
+    // An annotative style sizes its features by the annotation scale; the
+    // DIMSCALE it still stores is inert.
+    if style.annotative {
+        style.dimscale = 0.0;
+    }
+
     // Negative DIMLFAC applies only in paper space, and there only to a
     // dimension that measures model space through a viewport. The associative
     // record stores the applied factor; zero marks paper-space geometry whose