fix(pdf): follow-ups to the PDF underlay merge

- Pin cadcodec upstream at d290dbe (the merged underlay change) and
  cadkernel at 4134ae3, which follows it; drop the fork patch, move the
  plugin-API and web-worker crates and the Python plugin lock to the same
  codec so one copy is built.
- "Import as block" with raster images left IMAGE entities without an
  image definition: block definition now creates it like add_entity does,
  through one shared helper.
- The three preview outlines (attach frame, clip boundary, import area)
  stay f64 instead of casting world points to f32.
- Page size / total / PDF scale entries use the catalog's positional
  placeholder; the bare {name} form failed to format in 20 locales.
- The Underlay Layers bulb is the SVG layer icon, not a text glyph.
- PDF dialogs use the shared dialog buttons and radios.
- Options opened from a PDF dialog clears its saved state on return.
- Paper-space underlay background reuses the model block handle already
  resolved; dead `let _ = i` lines and a misplaced doc comment removed.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

src/modules/insert/pdf_import.rs

@@ -414,10 +414,9 @@ impl CadCommand for PdfImportCommand {
             }
             _ => return None,
         };
-        let mut points: Vec<[f32; 3]> =
-            ring.iter().map(|p| [p.x as f32, p.y as f32, p.z as f32]).collect();
+        let mut points: Vec<[f64; 3]> = ring.iter().map(|p| p.to_array()).collect();
         points.push(points[0]);
-        Some(WireModel::solid("pdf_import_area".into(), points, WireModel::CYAN, false))
+        Some(WireModel::solid_f64("pdf_import_area".into(), points, WireModel::CYAN, false))
     }
 }