Mark topbar nav arrows as visibly disabled until history wires up

The back/forward arrows in the topbar were styled as live buttons
(cursor_pointer, hover swap) but they had no on_click — they were
clickable affordances that did nothing. Per the "no fake handlers"
rule that's worse than no button at all: it lies to the user.

Pull the cursor and hover off, drop the text color to INK_5 so they
read as the design's `disabled` state (`var(--ely-ink-5)`), and
leave them untouched until real per-tab history lands in
BrowserCore. When the navigation API arrives the call site can
swap to a live variant.

crates/ely_app/src/shell/chrome/topbar.rs

@@ -203,6 +203,11 @@ where
         .into_any_element()
 }
 
+/// Topbar nav arrow placeholder. Per-tab back/forward history is not yet
+/// wired through `BrowserCore`, so the buttons render in the design's
+/// `disabled` state — visible at INK_5, no hover, no cursor pointer —
+/// to honor the "no fake handlers, no mockup" rule. When real history
+/// navigation lands the caller can flip these to a clickable variant.
 fn render_nav_arrow(id: &'static str, icon: IconName) -> AnyElement {
     div()
         .id(SharedString::from(id))
@@ -211,10 +216,7 @@ fn render_nav_arrow(id: &'static str, icon: IconName) -> AnyElement {
         .flex()
         .items_center()
         .justify_center()
-        .cursor_pointer()
-        .text_color(rgb(colors::INK_3))
-        .hover(|style| style.bg(rgba(OMNIBAR_BG)).text_color(rgb(colors::INK)))
-        .active(|style| style.opacity(0.82))
+        .text_color(rgb(colors::INK_5))
         .child(icon)
         .into_any_element()
 }