Feat: demo songs

src/state/options.rs

@@ -27,6 +27,7 @@ pub enum OptionsFocus {
     MidiInput2,
     MidiInput3,
     ResetOnboarding,
+    LoadDemoOnStartup,
 }
 
 impl CyclicEnum for OptionsFocus {
@@ -55,6 +56,7 @@ impl CyclicEnum for OptionsFocus {
         Self::MidiInput2,
         Self::MidiInput3,
         Self::ResetOnboarding,
+        Self::LoadDemoOnStartup,
     ];
 }
 
@@ -77,6 +79,7 @@ const STANDALONE_ONLY: &[OptionsFocus] = &[
     OptionsFocus::MidiInput2,
     OptionsFocus::MidiInput3,
     OptionsFocus::ResetOnboarding,
+    OptionsFocus::LoadDemoOnStartup,
 ];
 
 /// Section layout: header line, divider line, then option lines.
@@ -113,6 +116,7 @@ const FULL_LAYOUT: &[(OptionsFocus, usize)] = &[
     (OptionsFocus::MidiInput3, 39),
     // blank=40, ONBOARDING header=41, divider=42
     (OptionsFocus::ResetOnboarding, 43),
+    (OptionsFocus::LoadDemoOnStartup, 44),
 ];
 
 impl OptionsFocus {

src/state/ui.rs

@@ -79,6 +79,8 @@ pub struct UiState {
     pub zoom_factor: f32,
     pub window_width: u32,
     pub window_height: u32,
+    pub load_demo_on_startup: bool,
+    pub demo_index: usize,
 }
 
 impl Default for UiState {
@@ -127,6 +129,8 @@ impl Default for UiState {
             zoom_factor: 1.5,
             window_width: 1200,
             window_height: 800,
+            load_demo_on_startup: true,
+            demo_index: 0,
         }
     }
 }