feat(ux): shared PageTitle/SectionTitle primitive, adopt app-wide

- new components/ui/page-title.tsx (PageHeader/PageTitle/SectionTitle)
- every page heading routed through PageTitle (one source of truth
  for the page-title style; identical render)
- members restricted-directory screen now uses the standard
  PageHeader bar instead of an off-style mono heading

app/(app)/dashboard/page.tsx

@@ -2,6 +2,7 @@ import { createClient } from '@/lib/supabase/server'
 import Link from 'next/link'
 import { redirect } from 'next/navigation'
 import type { Tables } from '@/types/database'
+import { PageTitle } from '@/components/ui/page-title'
 
 function IcoUsers({ className }: { className?: string }) {
   return <svg className={className} fill="none" stroke="currentColor" viewBox="0 0 24 24"><path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M17 20h5v-2a3 3 0 00-5.356-1.857M17 20H7m10 0v-2c0-.656-.126-1.283-.356-1.857M7 20H2v-2a3 3 0 015.356-1.857M7 20v-2c0-.656.126-1.283.356-1.857m0 0a5.002 5.002 0 019.288 0M15 7a3 3 0 11-6 0 3 3 0 016 0zm6 3a2 2 0 11-4 0 2 2 0 014 0zM7 10a2 2 0 11-4 0 2 2 0 014 0z" /></svg>
@@ -97,7 +98,7 @@ export default async function DashboardPage() {
   return (
     <div className="min-h-screen bg-background">
       <div className="bg-sidebar px-4 md:px-6 py-3 flex items-center justify-between">
-        <h1 className="text-white font-sans text-lg font-semibold">Dashboard</h1>
+        <PageTitle>Dashboard</PageTitle>
         <Link href="/tasks" className="flex items-center gap-1.5 bg-primary text-white text-xs font-sans px-3 py-1.5 rounded hover:bg-primary/90 transition">
           <IcoPlus className="w-3.5 h-3.5" />
           <span className="hidden sm:inline">Quick Task</span>