Composite glass: inset highlights, blink, fade, panel tint

Closes the three "platform-impossible" gaps from the design audit
without resorting to hacks or shaders.

* chrome::glass — `render_inner_highlight(radius)` paints the design's
  `box-shadow: inset 0 0 0 1px` ring as an absolute overlay div with a
  1 px top-edge highlight sliver. GPUI 0.2.2's BoxShadow has no inset
  flag, so the composite is the only way to keep the panel content
  unclipped while the ring rides on top.
* chrome::animations — `blink` and `fade_in` wrap GPUI's first-class
  `with_animation` driver. Square-wave caret in the command header,
  180 ms opacity ramp on the command backdrop and workspace
  disclosure list.
* chrome::sidebar — panel_bg now tints toward the active wallpaper
  theme so the wallpaper bleeds through every glass surface, the
  closest honest substitute for backdrop-filter without a shader pass.
* command_overlay split: row helpers move to chrome::command_rows so
  command_overlay drops from 504 → 232 lines, well under the 500-line
  ceiling. No behavior change.

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

crates/ely_app/src/shell/sidebar.rs

@@ -13,6 +13,7 @@ use gpui_component::{
     button::{Button, ButtonVariants},
 };
 
+use super::chrome::glass::render_inner_highlight;
 use super::chrome::panel_bg;
 use super::{ElyShell, ShellState, render::tab_profile_label};
 use crate::ToggleSidebar;
@@ -37,6 +38,7 @@ impl ElyShell {
         div()
             .w(px(sidebar_width))
             .h_full()
+            .relative()
             .flex()
             .flex_col()
             .items_center()
@@ -88,6 +90,7 @@ impl ElyShell {
                     self.render_compact_archived_button(index, archived_tab, cx)
                 },
             ))
+            .child(render_inner_highlight(spacing::RADIUS_CARD))
             .into_any_element()
     }