feat(ui): add configurable message timestamps and card rendering layout

crates/owlen-core/src/config.rs

@@ -722,6 +722,8 @@ pub struct UiSettings {
     pub show_cursor_outside_insert: bool,
     #[serde(default = "UiSettings::default_syntax_highlighting")]
     pub syntax_highlighting: bool,
+    #[serde(default = "UiSettings::default_show_timestamps")]
+    pub show_timestamps: bool,
 }
 
 impl UiSettings {
@@ -765,6 +767,10 @@ impl UiSettings {
         false
     }
 
+    const fn default_show_timestamps() -> bool {
+        true
+    }
+
     fn deserialize_role_label_mode<'de, D>(
         deserializer: D,
     ) -> std::result::Result<RoleLabelDisplay, D::Error>
@@ -831,6 +837,7 @@ impl Default for UiSettings {
             scrollback_lines: Self::default_scrollback_lines(),
             show_cursor_outside_insert: Self::default_show_cursor_outside_insert(),
             syntax_highlighting: Self::default_syntax_highlighting(),
+            show_timestamps: Self::default_show_timestamps(),
         }
     }
 }