fix(settings): use window-level keydown for Escape to close panel

Context: SettingsPanel used `onkeydown` on the panel div, but the div
never receives focus automatically when it opens. Escape key events go
to whatever element has focus (usually the editor), so the handler never
fires.

Solution: Move the Escape handler to `svelte:window onkeydown` so it
captures the key regardless of focus state. Guard with `isOpen` check
to avoid closing when already closed.

Files:
- src/lib/core/settings/SettingsPanel.svelte (77-81,83,86-93): replaced
  div-level onkeydown with svelte:window onkeydown, removed tabindex
  and a11y ignore comment (no longer needed)

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: diegorv

src/lib/core/settings/SettingsPanel.svelte

@@ -75,22 +75,21 @@
 	});
 
 	function handleKeydown(event: KeyboardEvent) {
-		if (event.key === 'Escape') {
+		if (event.key === 'Escape' && settingsPanelStore.isOpen) {
 			settingsPanelStore.close();
 		}
 	}
 </script>
 
+<svelte:window onkeydown={handleKeydown} />
+
 {#if settingsPanelStore.isOpen}
-	<!-- svelte-ignore a11y_no_noninteractive_element_interactions -->
 	<div
 		class="fixed top-0 right-0 z-40 flex flex-row overflow-hidden border-l border-border bg-settings-dialog-bg shadow-[-4px_0_12px_rgba(0,0,0,0.15)]"
 		style="bottom: 24px; width: 820px; max-width: 80vw;"
 		transition:fly={{ x: 820, duration: 200 }}
 		role="dialog"
 		aria-label="Settings"
-		tabindex="-1"
-		onkeydown={handleKeydown}
 	>
 		<!-- Sidebar -->
 		<nav class="flex w-48 shrink-0 flex-col gap-0.5 overflow-y-auto border-r border-border px-3 py-5 bg-settings-sidebar-bg">