SAVEAS version and binary DXF, default save version (fixes #421) (#431)

Squash of PR #431 by @vangel76.

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

docs/control-protocol.md

@@ -35,7 +35,7 @@ The server waits up to 60 s for the app to answer a request. After that it repli
 | `ui.click` / `ui.move` | `{x, y, button?, shift?}` | Real egui pointer events in screen points (reach every widget). |
 | `ui.drag` | `{x, y, to: [x, y], button?}` | Real press, move and release (drag the command line's top edge, the ViewCube ring…). |
 | `ui.key` / `ui.text` | `{key, cmd?, shift?, alt?}` / `{text}` | Synthetic keyboard input. |
-| `ui.set` | UiState fields | Show/hide palettes, toolbars, command line, ViewCube…; `theme: "system"\|"light"\|"dark"` (also `engine.execute` with `ui.theme {theme}`); `ui.inspect` reports the theme shown (`theme`: light/dark). `saveFormat: "dxf"\|"dwg"` (also `ui.saveformat {format}`) is the format Save As suggests for new drawings. |
+| `ui.set` | UiState fields | Show/hide palettes, toolbars, command line, ViewCube…; `theme: "system"\|"light"\|"dark"` (also `engine.execute` with `ui.theme {theme}`); `ui.inspect` reports the theme shown (`theme`: light/dark). `saveFormat: "dxf"\|"dwg"` (also `ui.saveformat {format}`) is the format Save As suggests for new drawings; `saveVersion: "2000"`…`"2018"` (also `ui.saveversion {version}`) the version it saves them in (SAVEAS also takes `version` and `binary` directly). |
 | `ui.resize` | `{width, height}` | Resize the window. |
 | `ui.focus` | | Activate the native window. Does not assign focus to a widget. |
 | `ui.screenshot` | `{path?}` | PNG of the window (needs a presented frame). |