RHL-038 fix(layout): update column width in AppShell and TopNav for consistent layout

components/app-shell/AppShell.jsx

@@ -9,7 +9,7 @@ export default function AppShell({ children }) {
 
 			{/* 
 				Layout strategy (2xl+):
-				- Center column is exactly 50% width.
+				- Center column is exactly 40% width.
 				- Left/right gutters are flexible.
 				- Sidebar is placed in the left gutter and aligned to the right edge,
 				  so it “docks” to the centered content without consuming its width.
@@ -19,7 +19,7 @@ export default function AppShell({ children }) {
 				- Sidebar is hidden (it would otherwise reduce main content width).
 			*/}
 			<div className="flex-1 px-4 py-4">
-				<div className="mx-auto grid w-full gap-4 2xl:grid-cols-[1fr_minmax(0,50%)_1fr]">
+				<div className="mx-auto grid w-full gap-4 2xl:grid-cols-[1fr_minmax(0,40%)_1fr]">
 					<aside className="hidden 2xl:col-start-1 2xl:block 2xl:justify-self-end">
 						{/* 
 							Sidebar width policy:

components/app-shell/TopNav.jsx

@@ -11,14 +11,14 @@ export default function TopNav() {
 		<header className="sticky top-0 z-50 w-full border-b bg-background/80 backdrop-blur">
 			{/* 
 				TopNav alignment strategy (2xl+):
-				- Use the same 60% center column as the AppShell content grid.
+				- Use the same 40% center column as the AppShell content grid.
 				- This keeps header content perfectly aligned with Explorer/Search.
 
 				Below 2xl:
 				- Full width for usability.
 			*/}
 			<div className="px-4">
-				<div className="mx-auto grid h-14 w-full items-center 2xl:grid-cols-[1fr_minmax(0,50%)_1fr]">
+				<div className="mx-auto grid h-14 w-full items-center 2xl:grid-cols-[1fr_minmax(0,40%)_1fr]">
 					<div className="flex items-center justify-between gap-3 2xl:col-start-2">
 						<div className="flex items-center gap-3">
 							<Link href="/" className="font-semibold tracking-tight">