PDF underlays: attach prompts and definitions, display adjustments and clipping, Properties, snapping, PDFCLIP and PDFIMPORT

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

src/command.rs

@@ -1556,6 +1556,8 @@ pub enum CmdResult {
     BatchCopy(Vec<Handle>, Vec<EntityTransform>),
     /// Erase `handle` and replace with new entities; command stays active.
     ReplaceEntity(Handle, Vec<EntityType>),
+    /// Import the vector content of a PDF underlay (PDFIMPORT); ends the command.
+    PdfImport(crate::modules::insert::pdf_import::PdfImportRequest),
     /// Update one entity in place, preserve its handle, and end the command.
     UpdateEntityAndFinish {
         handle: Handle,
@@ -2844,6 +2846,12 @@ pub trait CadCommand: Send {
         None
     }
 
+    /// If this command attaches a PDF page: its file and page. The host
+    /// creates (or reuses) the definition with the committed underlay.
+    fn pdf_attach_source(&self) -> Option<(String, String)> {
+        None
+    }
+
     /// The block reference an ATTEDIT pick has resolved to, awaiting the
     /// attribute editor dialog; else None.
     fn attedit_pending_handle(&self) -> Option<acadrust::Handle> {