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 <noreply@anthropic.com>

locales/ru-RU/opencadstudio.ftl

@@ -3509,7 +3509,7 @@ annotate =
     .tolerance-specify-insertion-point = TOLERANCE Укажите точку вставки:
 
 insert =
-    .pdfui-pdf-scale = PDF scale: {scale}:1
+    .pdfui-pdf-scale = PDF scale: __ocs_fmt_0__:1
     .pdfui-specify-insertion-point = Specify insertion point:
     .pdfui-no-pdf-underlays = No PDF underlays found.
     .pdfui-imports-the-geometry-fills-raster-images-and-text-of-a-pdf-f = Imports the geometry, fills, raster images and text of a PDF file as drawing objects.
@@ -3518,8 +3518,8 @@ insert =
     .pdfui-rotation = Rotation:
     .pdfui-scale = Scale:
     .pdfui-specify-insertion-point-on-screen = Specify insertion point on-screen
-    .pdfui-page-size-size = Page size: {size}
-    .pdfui-total-count = Total: {count}
+    .pdfui-page-size-size = Page size: __ocs_fmt_0__
+    .pdfui-total-count = Total: __ocs_fmt_0__
     .pdfui-page = Page:
     .pdfui-page-to-import = Page to import
     .pdfui-infer-linetypes-from-collinear-dashes = Infer linetypes from collinear dashes