Drop unwired shortcut hints from command overlay footer

Footer advertised `⌘↵ open in split` and `⇥ filter`, but neither is
plumbed through `on_command_overlay_key_down` — the dispatch only
handles up / down / enter. Per the no-fake-handlers rule a hint that
doesn't fire is worse than no hint, so trim the footer to just the
two shortcuts that actually work. The split/filter hints can come
back the moment the dispatch grows to handle them.

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

@@ -16,10 +16,12 @@ pub(crate) fn render_command_footer() -> AnyElement {
         .text_size(px(10.5))
         .text_color(rgb(colors::INK_3))
         .bg(rgba(FOOTER_BG))
+        // Only the shortcuts that actually do something today.
+        // `⌘↵` (split-on-open) and `⇥` (filter) are real product
+        // features but not yet wired through the command overlay's
+        // key dispatch — listing them here would be a fake hint.
         .child(footer_chunk("↑↓", "navigate"))
         .child(footer_chunk("↵", "open"))
-        .child(footer_chunk("⌘↵", "open in split"))
-        .child(footer_chunk("⇥", "filter"))
         .child(
             div()
                 .ml_auto()