feat(clipboard): paste menu with paste-to-original and paste-as-block

Turn the ribbon Clipboard "Paste" button into a dropdown:
- Paste — existing pick-a-point paste.
- Paste to Original Coordinates — drops the clipboard at its source
  coordinates with no prompt.
- Paste as Block — wraps the clipboard contents in a new block definition
  and starts an interactive insert (prompts for the drop point, with the
  geometry rubber-banding under the cursor).

Also fixes two bugs the new commands exposed:
- entities_centroid summed the NaN separator points wire models carry,
  so the paste base point came out NaN; non-finite points are now
  skipped. A NaN base previously froze block tessellation outright.
- PASTEORIG added clipboard entities with their original handles
  (duplicates on same-document paste); it now goes through
  add_entity_clone and merges referenced records like the other pastes.

Co-Authored-By: Claude Opus 4.8 <[email protected]>

src/modules/draw/clipboard/paste.rs

@@ -2,11 +2,22 @@
 
 use crate::modules::{IconKind, ModuleEvent, ToolDef};
 
+/// Shared icon for the Paste button and its dropdown entries.
+pub const ICON: IconKind = IconKind::Svg(include_bytes!("../../../../assets/icons/paste.svg"));
+
+/// Paste-menu entries: (command id, label, icon). The first is the default
+/// fired by clicking the button body; the rest open from the ▾.
+pub const MENU_ITEMS: &[(&str, &str, IconKind)] = &[
+    ("PASTECLIP", "Paste", ICON),
+    ("PASTEORIG", "Paste to Original Coordinates", ICON),
+    ("PASTEBLOCK", "Paste as Block", ICON),
+];
+
 pub fn tool() -> ToolDef {
     ToolDef {
         id: "PASTECLIP",
         label: "Paste",
-        icon: IconKind::Svg(include_bytes!("../../../../assets/icons/paste.svg")),
+        icon: ICON,
         event: ModuleEvent::Command("PASTECLIP".to_string()),
     }
 }
@@ -62,3 +73,5 @@ impl CadCommand for PasteCommand {
 
 // ── Autocomplete registry ─────────────────────────────────
 inventory::submit!(crate::command::CommandRegistration { names: &["PASTECLIP", "PC"] });  // PasteCommand
+inventory::submit!(crate::command::CommandRegistration { names: &["PASTEORIG"] });
+inventory::submit!(crate::command::CommandRegistration { names: &["PASTEBLOCK"] });

src/modules/draw/mod.rs

@@ -214,7 +214,13 @@ impl CadModule for DrawModule {
             RibbonGroup {
                 title: "Clipboard",
                 tools: vec![
-                    RibbonItem::LargeTool(paste::tool()),
+                    RibbonItem::LargeDropdown {
+                        id: "PASTE_MENU",
+                        label: "Paste",
+                        icon: paste::ICON,
+                        items: paste::MENU_ITEMS.to_vec(),
+                        default: "PASTECLIP",
+                    },
                     copy_clip::tool().into(),
                     cut::tool().into(),
                 ],

src/modules/insert/insert_block.rs

@@ -37,6 +37,10 @@ pub struct InsertBlockCommand {
     step: Step,
     /// Pending Insert entity stored while attr-filling is in progress.
     pending_insert: Option<Insert>,
+    /// Optional drag preview: the block's wire geometry plus the base point it
+    /// is measured from, so `on_preview_wires` can rubber-band it to the
+    /// cursor. Set by paste-as-block; empty for a plain INSERT.
+    preview: Option<(Vec<WireModel>, Vec3)>,
 }
 
 impl InsertBlockCommand {
@@ -45,6 +49,20 @@ impl InsertBlockCommand {
             available,
             step: Step::Name,
             pending_insert: None,
+            preview: None,
+        }
+    }
+
+    /// Start the command already locked to `name`, skipping the name prompt and
+    /// going straight to "specify insertion point". `preview_wires` (measured
+    /// from `base`) rubber-band under the cursor. Used by paste-as-block, which
+    /// has just defined the block and only needs the drop point.
+    pub fn new_for_block(name: String, preview_wires: Vec<WireModel>, base: Vec3) -> Self {
+        Self {
+            available: vec![name.clone()],
+            step: Step::Point { name },
+            pending_insert: None,
+            preview: Some((preview_wires, base)),
         }
     }
 }
@@ -138,8 +156,14 @@ impl CadCommand for InsertBlockCommand {
         }
     }
 
-    fn on_preview_wires(&mut self, _pt: Vec3) -> Vec<WireModel> {
-        vec![]
+    fn on_preview_wires(&mut self, pt: Vec3) -> Vec<WireModel> {
+        match (&self.step, &self.preview) {
+            (Step::Point { .. }, Some((wires, base))) => {
+                let delta = pt - *base;
+                wires.iter().map(|w| w.translated(delta)).collect()
+            }
+            _ => vec![],
+        }
     }
 
     fn attreq_set_attdefs(&mut self, attdefs: Vec<(String, String, String)>) {