feat(ui): add cross-platform window control styles

Persist automatic and explicit macOS, Windows, GNOME, and minimal control presets with localized settings and platform-aware fallback.

Refs #31

src-tauri/src/ipc.rs

@@ -214,6 +214,23 @@ pub enum Theme {
     Nord,
 }
 
+#[derive(Clone, Debug, Serialize, Deserialize, TS)]
+#[serde(rename_all = "lowercase")]
+#[ts(export, export_to = "../../src/bindings/")]
+pub enum WindowControlStyle {
+    Auto,
+    Macos,
+    Windows,
+    Gnome,
+    Minimal,
+}
+
+impl Default for WindowControlStyle {
+    fn default() -> Self {
+        Self::Auto
+    }
+}
+
 #[derive(Clone, Debug, Serialize, Deserialize, TS)]
 #[serde(rename_all = "lowercase")]
 #[ts(export, export_to = "../../src/bindings/")]
@@ -295,6 +312,8 @@ pub struct SchedulerSettings {
 pub struct PersistedSettings {
     pub theme: Theme,
     #[serde(default)]
+    pub window_control_style: WindowControlStyle,
+    #[serde(default)]
     pub calendar_preference: CalendarPreference,
     #[serde(default = "default_language_preference")]
     pub language: String,