fix(android): keep the toolbar out of the status and navigation bars (Issue #50)

NativeActivity draws the whole window, also below the system bars, so the
top toolbar button lay under the status bar and taps there went to
Android (no other notebook could be opened). InkActivity now reports the
system bar and cutout insets; the app shrinks egui's screen rect to the
free area and adds the side insets to the page centering. The page itself
still scrolls below the bars.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/app.rs

@@ -4150,6 +4150,17 @@ pub fn run_with(
                             raw_input.events.extend(events);
                             ui_state.queued_actions.extend(actions);
                         }
+                        // Keep the UI out of system bars and cutouts (Android, Issue #50)
+                        let safe_area = platform::safe_area_insets();
+                        if let Some(rect) = raw_input.screen_rect.filter(|_| safe_area != [0.0; 4])
+                        {
+                            let ppp = egui_ctx.pixels_per_point();
+                            let [left, top, right, bottom] = safe_area.map(|v| v / ppp);
+                            raw_input.screen_rect = Some(egui::Rect::from_min_max(
+                                rect.min + egui::vec2(left, top),
+                                rect.max - egui::vec2(right, bottom),
+                            ));
+                        }
                         egui_ctx.begin_frame(raw_input);
 
                         // 2. Auswahl-Overlay rendern (Bounding Box, Griffe, Lasso)
@@ -4182,8 +4193,8 @@ pub fn run_with(
                         let reserved =
                             ui_state.sidebar_reserved_width() * window.scale_factor() as f32;
                         let (inset_left, inset_right) = match ui_state.sidebar_side {
-                            SidebarSide::Left => (reserved, 0.0),
-                            SidebarSide::Right => (0.0, reserved),
+                            SidebarSide::Left => (reserved + safe_area[0], safe_area[2]),
+                            SidebarSide::Right => (safe_area[0], reserved + safe_area[2]),
                         };
                         if canvas.set_ui_insets(inset_left, inset_right) {
                             window.request_redraw();