Merge pull request #383 from KevinGriffin-new/fix/pdf-export

Never fail silently on PDF export; add EXPORTPDF <path> (#369).

The export flow handed off to an async rfd save dialog and mapped a None
result straight to Task::none(). On Linux None also means the dialog never
opened (broken XDG portal / missing zenity), and rfd reports that only via
log, so PDF export could end in total silence. The dialog-None arms now
print a message pointing at EXPORTPDF <path>, and EXPORT/EXPORTPDF take an
optional path that exports straight to a file with no dialog — the
workaround where the native dialog can't open, and a headless entry point.

Conflict: the fix (display.rs, file.rs, mod.rs, COMMANDS.md) auto-merged;
only the additive test block in automation.rs conflicted. Resolved by
keeping main's tests and adding the two #369 tests.

# Conflicts:
#	src/app/automation.rs

src/app/automation.rs

@@ -714,6 +714,56 @@ mod tests {
         }
     }
 
+    #[test]
+    fn exportpdf_with_explicit_path_writes_pdf_without_dialog() {
+        // EXPORTPDF <path> must export straight to the given file — no save
+        // dialog — and confirm on the command line. This is the dialog-free
+        // export path added for #369 (Export to PDF silently did nothing when
+        // the native save dialog could not open).
+        let mut app = OpenCADStudio::new_for_test();
+        app.automation_op(r#"{"op":"new"}"#);
+        app.automation_op(r#"{"op":"run","cmd":"LINE 0,0 100,50"}"#);
+
+        let path = std::env::temp_dir().join(format!("ocs_test_369_{}.pdf", std::process::id()));
+        let _ = std::fs::remove_file(&path);
+        let start = app.command_line.history.len();
+        let _ = app.run_command_line(&format!("EXPORTPDF {}", path.display()));
+        let out: String = app.command_line.history[start..]
+            .iter()
+            .map(|e| e.text.as_str())
+            .collect::<Vec<_>>()
+            .join("\n");
+        assert!(out.contains("Exported"), "no export confirmation: {out:?}");
+
+        let bytes = std::fs::read(&path).expect("EXPORTPDF <path> should write the file");
+        assert!(bytes.starts_with(b"%PDF"), "output is not a PDF");
+        assert!(bytes.len() > 200, "suspiciously small PDF: {}", bytes.len());
+        let _ = std::fs::remove_file(&path);
+    }
+
+    #[test]
+    fn cancelled_pdf_save_dialog_reports_on_command_line() {
+        // The save dialog resolving to None (cancelled, or it never opened —
+        // e.g. a broken XDG portal) must leave a visible message, not silence.
+        // Regression for #369.
+        use crate::app::Message;
+        let mut app = OpenCADStudio::new_for_test();
+        app.automation_op(r#"{"op":"new"}"#);
+        for msg in [Message::PlotExportPath(None), Message::PlotWindowExportPath(None)] {
+            let start = app.command_line.history.len();
+            let _ = app.update(msg);
+            let out: String = app.command_line.history[start..]
+                .iter()
+                .map(|e| e.text.as_str())
+                .collect::<Vec<_>>()
+                .join("\n");
+            assert!(
+                out.contains("EXPORTPDF"),
+                "dialog-None must mention the EXPORTPDF fallback: {out:?}"
+            );
+        }
+    }
+
     #[test]
     fn handing_over_an_already_open_drawing_switches_to_its_tab() {
         // Double-clicking a drawing that is already open should land on the tab