Restructure topbar to match design's omnibar + right action cluster

Move topbar rendering into chrome::topbar so it does not bloat render.rs.
The omnibar now ends in two glass chips (filters + favorite star) inline
with the address input, matching the design's pill layout. The toolbar
right cluster is rebuilt as copy-url, downloads, theme, and menu icons:

- Copy chip writes the active tab's URL to the system clipboard.
- Downloads opens ely://downloads (existing internal route).
- Theme chip routes to ely://settings/appearance for now (a Light/Dark
  toggle still has to live in appearance settings before it can be a
  one-shot).
- Menu opens ely://settings.

The pin/new-tab buttons are removed; they were not part of the design's
topbar. Pinning still works through the favorite chip + sidebar
selection state, and Cmd+T continues to create tabs.

crates/ely_app/src/shell/navigation.rs

@@ -1,5 +1,5 @@
 use ely_domain::UrlText;
-use gpui::{Context, Window};
+use gpui::{ClipboardItem, Context, Window};
 use gpui_component::input::SelectAll;
 
 use super::{ElyShell, ShellState};
@@ -64,4 +64,12 @@ impl ElyShell {
         });
         window.dispatch_action(Box::new(SelectAll), cx);
     }
+
+    pub(super) fn copy_active_tab_url(&mut self, _window: &mut Window, cx: &mut Context<Self>) {
+        if let ShellState::Ready(core) = &self.state
+            && let Ok(tab) = core.active_tab()
+        {
+            cx.write_to_clipboard(ClipboardItem::new_string(tab.url().as_str().to_string()));
+        }
+    }
 }