feat: embed images (OLE2FRAME), print pipeline fixes, plot prefs, community fonts

- IMAGEEMBED: pack raster images into OLE2FRAME entities so a .dwg is
  self-contained; 'Embed Image' entry in the XREF attach menu; control/MCP
  op embed_image for external tools; dxf_name for OLE2FRAME queries.
- Scene: populate_images_from_document now rebuilds OLE2FRAME and PDF
  underlay models too (they used to vanish after any XREF op).
- Printing: add PRINTER_ENUM_NETWORK pass when listing printers; GDI
  spooler fallback (hayro raster at 300 DPI + StretchDIBits) for hosts
  whose PDF handler registers no print verb; DEVMODE orientation with a
  90-degree raster rotation fallback for v4 drivers; fix the fit-scale
  precedence bug that printed blank pages.
- PDF export dialogs on Windows use the async file dialog so the native
  overwrite confirmation no longer deadlocks the UI thread.
- Plot dialog: persist the chosen printer (saved on selection) and the
  picked plot window across sessions; page setups with no device no
  longer reset the output device.
- Community fonts: detect unresolvable .shx references on open and offer
  a download from the repository's fonts/ folder (contribution guide in
  fonts/README.md); custom font source URL setting for intranet font
  servers; downloaded fonts resolve from the per-user fonts directory.

src/entities/names.rs

@@ -143,6 +143,7 @@ pub fn dxf_name(e: &EntityType) -> &'static str {
         EntityType::MLine(_) => "MLINE",
         EntityType::RasterImage(_) => "RASTERIMAGE",
         EntityType::Wipeout(_) => "WIPEOUT",
+        EntityType::Ole2Frame(_) => "OLE2FRAME",
         EntityType::Underlay(_) => "UNDERLAY",
         EntityType::AttributeDefinition(_) => "ATTDEF",
         EntityType::AttributeEntity(_) => "ATTRIB",

src/entities/text_support.rs

@@ -39,6 +39,12 @@ pub fn resolve_text_style(style_name: &str, document: &CadDocument) -> ResolvedT
                         .map(std::path::Path::new)
                         .and_then(|p| p.parent());
                     crate::io::resolve_image_file(file, base)
+                        // Fonts fetched from the community repository live in
+                        // the per-user fonts folder — search it last.
+                        .or_else(|| {
+                        crate::io::font_repo::local_font_file(file)
+                            .map(|path| path.to_string_lossy().into_owned())
+                    })
                 })
                 .flatten();
             if let Some(p) = shx_path {