feat(pdf): searchable text layer with per-style subset font embedding

Real BT/Tj text objects ride alongside the vector outlines (Tr 3,
zero visual change): runs preserved at layout time, TTF styles embedded
as allsorts subsets with ToUnicode, width-matched Tm, clip-culled.
WireModel literals moved to ..Default::default() tails.

src/modules/annotate/dim_baseline.rs

@@ -755,7 +755,9 @@ fn preview_for_dimension(dimension: &Dimension) -> WireModel {
         plinegen: true,
         fill_tris: Vec::new(),
         fill_tris_low: Vec::new(),
-    }
+    
+        ..Default::default()
+}
 }
 
 fn linear_preview(