R7.6: Windows and Linux print (#3)

Windows prints through the system dialog at the document's paper;
Linux through the desktop portal, the dialog's choices laid out by Ely.
Round 3 findings fixed without a further review, as the rules say.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

crates/ely-ui/src/shell/root.rs

@@ -379,7 +379,7 @@ mod tests {
             })
             .expect("the window lives");
         cx.run_until_parked();
-        // Save without a document is blocked; so is Print unbuilt.
+        // Save without a document is blocked.
         window
             .update(cx, |_, window, cx| root.update(cx, |root, cx| root.run_from_palette("file.save", window, cx)))
             .expect("the window lives");