Fix incorrect minimum_contrast comment (#34710)

Actual default is 45


fd05f17fa7/assets/settings/default.json (L1402)

Release Notes:

- N/A

crates/terminal/src/terminal_settings.rs

@@ -248,7 +248,7 @@ pub struct TerminalSettingsContent {
     /// - 75: Minimum for body text
     /// - 90: Preferred for body text
     ///
-    /// Default: 0 (no adjustment)
+    /// Default: 45
     pub minimum_contrast: Option<f32>,
 }