Header round 6 (owner): the top bar grows to 60px — aligned to the sidebar's LH band

h-10 → h-15 (60px) in both the chat header and the /chat/new draft
header. 60px is an alignment, not just a size: it equals the sidebar's
LH wordmark band, so the header's border-b continues that band's bottom
edge as one horizontal line across the app — the sidebar's 'New session'
row begins exactly where the chat column's chrome ends.

Live: header border-b at y=60, wordmark band bottom at y=60. Gates:
typecheck, lint, 469/469.

components/new-session.tsx

@@ -77,7 +77,9 @@ export function DraftShell({
 	return (
 		<div className="flex h-dvh">
 			<div className="flex min-w-0 flex-1 flex-col">
-				<header className="relative flex h-10 items-center gap-3 px-3">
+				{/* h-15 (60px) matches the chat header and the sidebar's LH wordmark
+			    band (owner, round 6). */}
+			<header className="relative flex h-15 items-center gap-3 px-3">
 					<SidebarToggle />
 					<div className="min-w-0 flex-1 truncate font-title text-2xl tracking-tight">New session</div>
 					<PhaseChip phase="probe" />