Match split-pane header to design (accent dot + tab title)

The design's split.jsx Pane header leads with an 8 px brand-accent dot,
the lock indicator, host name in INK, then the tab title in INK_4.
The previous header rendered a 24 px brand glyph plus the URL path —
visually heavier and less informative once both panes share most of
their URL prefix.

* brand_glyph: `brand_accent_color(brand)` and `accent_color_for_host`
  collapse each Brand to one design-matching dot color (Figma 7c6cf7,
  Linear 5e6ad2, etc.).
* split_pane: 32 → 30 px header, glyph → 8 px dot, URL path → tab
  title in INK_4. `pane_path_label` deleted; nothing else used it.

cargo test --workspace: 440 passed, 0 failed.

crates/ely_app/src/shell/splits.rs

@@ -11,7 +11,7 @@ use gpui_component::{
 };
 
 use super::chrome::{
-    pane_host_label, pane_path_label, pane_url_is_secure, render_compact_split_canvas,
+    pane_host_label, pane_url_is_secure, render_compact_split_canvas,
     render_split_pane_header,
 };
 use super::{ElyShell, ShellState};
@@ -190,14 +190,8 @@ impl ElyShell {
         let close_tab_id = tab.id().clone();
         let border = if active { colors::ACCENT } else { colors::HAIRLINE_STRONG };
         let host = pane_host_label(tab);
-        let path = pane_path_label(tab);
+        let title = tab.title().to_string();
         let secure = pane_url_is_secure(tab);
-        let glyph_initial = tab
-            .title()
-            .chars()
-            .next()
-            .unwrap_or('?')
-            .to_string();
 
         div()
             .id(SharedString::from(format!("split-pane-{}", tab.id().as_str())))
@@ -217,7 +211,7 @@ 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, glyph_initial, close_tab_id, cx))
+            .child(render_split_pane_header(host, title, secure, close_tab_id, cx))
             .child(div().flex_1().min_h_0().overflow_hidden().child(if compact_canvas {
                 render_compact_split_canvas(tab)
             } else {