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>

src/command.rs

@@ -1556,13 +1556,13 @@ pub enum CmdResult {
     BatchCopy(Vec<Handle>, Vec<EntityTransform>),
     /// Erase `handle` and replace with new entities; command stays active.
     ReplaceEntity(Handle, Vec<EntityType>),
-    /// Attach PDF pages: each page's underlay with its file (as stored) and
-    /// page; the host creates or reuses the definitions and commits them all
-    /// in one undo step, then ends the command.
     /// Open the PDF Import Settings dialog; the command keeps its prompt.
     OpenPdfImportSettings,
     /// Import a page of a file (PDFIMPORT File); ends the command.
     PdfImportFile(crate::modules::insert::pdf_import::PdfFileImport),
+    /// Attach PDF pages: each page's underlay with its file (as stored) and
+    /// page; the host creates or reuses the definitions and commits them all
+    /// in one undo step, then ends the command.
     AttachPdfPages {
         path: String,
         pages: Vec<(String, EntityType)>,