feat: add adaptive app appearance

crates/app/src/domain.rs

@@ -32,6 +32,35 @@ impl IconStyle {
     }
 }
 
+#[derive(Clone, Copy, Debug, Default, Deserialize, Eq, PartialEq, Serialize)]
+#[serde(rename_all = "lowercase")]
+pub enum AppearanceMode {
+    Light,
+    Dark,
+    #[default]
+    #[serde(other)]
+    Auto,
+}
+
+impl AppearanceMode {
+    pub fn index(self) -> i32 {
+        match self {
+            Self::Auto => 0,
+            Self::Light => 1,
+            Self::Dark => 2,
+        }
+    }
+
+    pub fn from_index(index: i32) -> Option<Self> {
+        match index {
+            0 => Some(Self::Auto),
+            1 => Some(Self::Light),
+            2 => Some(Self::Dark),
+            _ => None,
+        }
+    }
+}
+
 #[derive(Clone, Deserialize, Serialize)]
 pub struct Server {
     pub name: String,
@@ -54,6 +83,8 @@ pub struct Preferences {
     pub pull_status: String,
     #[serde(default)]
     pub icon_style: IconStyle,
+    #[serde(default)]
+    pub appearance: AppearanceMode,
 }
 
 impl Default for Preferences {
@@ -65,6 +96,7 @@ impl Default for Preferences {
             issue_status: open_status(),
             pull_status: open_status(),
             icon_style: IconStyle::default(),
+            appearance: AppearanceMode::default(),
         }
     }
 }