Brand glyph + reload control in split pane header

Replace the colored accent dot in each split pane header with the
host's brand glyph, and add the design's reload control next to the
close glyph. The header height bumps from 30 to 32 px so the 16 px
glyph sits cleanly between the 11 px lock and host text.

crates/ely_app/src/shell/splits.rs

@@ -192,7 +192,12 @@ impl ElyShell {
         let host = pane_host_label(tab);
         let path = pane_path_label(tab);
         let secure = pane_url_is_secure(tab);
-        let dot_color = if active { colors::ACCENT } else { colors::INK_4 };
+        let glyph_initial = tab
+            .title()
+            .chars()
+            .next()
+            .unwrap_or('?')
+            .to_string();
 
         div()
             .id(SharedString::from(format!("split-pane-{}", tab.id().as_str())))
@@ -212,7 +217,7 @@ impl ElyShell {
             .on_click(cx.listener(move |shell, _, window, cx| {
                 shell.select_tab(&tab_id, window, cx);
             }))
-            .child(render_split_pane_header(host, path, secure, dot_color, close_tab_id, cx))
+            .child(render_split_pane_header(host, path, secure, glyph_initial, close_tab_id, cx))
             .child(div().flex_1().min_h_0().overflow_hidden().child(if compact_canvas {
                 render_compact_split_canvas(tab)
             } else {