desktop: tri-platform window chrome, packaging and draft-release CI

components/graph-view.tsx

@@ -1590,7 +1590,7 @@ export function GraphView({
 			    against the full-bleed parent) — the row NEVER wraps (owner
 			    rejected the two-row fold); in narrow windows the search is
 			    the flexible element and shrinks instead. */}
-			<div className="lh-no-drag absolute right-2 top-2 z-10 flex max-w-[calc(100%-5.5rem)] flex-col items-end gap-2">
+			<div className="lh-no-drag lh-wco-floating absolute right-2 top-2 z-10 flex max-w-[calc(100%-5.5rem)] flex-col items-end gap-2">
 			{/* z-20 (2026-09-20): the row paints above the cost number below
 			    it — without this, the later-in-DOM cost control layered over
 			    the settings/coverage dropdowns (owner report), still hoverable

components/minimal-home.tsx

@@ -180,7 +180,7 @@ export function MinimalHome({
 			    window instead. Node search and the render-settings gear are
 			    canvas things and stay gone; Import ALWAYS renders (the
 			    entry law). */}
-			<div className="lh-no-drag absolute right-2 top-2 z-10 flex max-w-[calc(100%-5.5rem)] flex-col items-end gap-2">
+			<div className="lh-no-drag lh-wco-floating absolute right-2 top-2 z-10 flex max-w-[calc(100%-5.5rem)] flex-col items-end gap-2">
 				<div className="flex min-w-0 items-start gap-2">
 					<div className="graph-chrome-fade-in shrink-0 rounded-xl border bg-card/85 px-1 py-[3px] shadow-lg backdrop-blur">
 						<Hint label="Every reasoning chain" side="bottom">

components/sidebar.tsx

@@ -56,6 +56,8 @@ declare global {
 	interface Window {
 		/** Preload bridge (electron/preload.cjs) — Electron only, absent in the browser. */
 		lh?: {
+			/** Read-only host OS; determines the native-control gutter. */
+			platform?: string;
 			expandWindow: () => void;
 			/** The zoom truth (owner round 7): subscribes to "lh:zoom" pushes; returns unsubscribe. */
 			onZoom?: (cb: (factor: number) => void) => () => void;
@@ -91,6 +93,7 @@ export function SidebarProvider({ children }: { children: React.ReactNode }) {
 		// and in the plain browser the class never appears.
 		if (IS_ELECTRON) {
 			document.documentElement.classList.add("lh-electron");
+			document.documentElement.dataset.lhPlatform = window.lh?.platform ?? "";
 		}
 
 		// THE ZOOM TRUTH (owner round 7, 2026-10-05): ⌘±/⌘0 zoom the UI

components/top-bar.tsx

@@ -53,7 +53,7 @@ export function TopBar({
 	return (
 		<header
 			onMouseDown={onMouseDown}
-			className={`${drag ? "lh-drag " : ""}flex h-15 select-none items-center gap-3 border-b border-border px-3`}
+			className={`${drag ? "lh-drag " : ""}lh-wco-gutter flex h-15 select-none items-center gap-3 border-b border-border px-3`}
 		>
 			<SidebarToggle />
 			{children}