Rename Brain to Upload material and Instruction to Brain and AI

Upload material (/upload) drops the metric cards for a larger upload box
above the material list; Brain and AI moves to /brain. Old paths redirect.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/components/AppLayout.tsx

@@ -17,8 +17,8 @@ export const NAV_GROUPS: { label: Key; items: { to: string; label: Key; icon: Ic
   {
     label: 'nav.settings',
     items: [
-      { to: '/brain', label: 'nav.brain', icon: 'brain' },
-      { to: '/instruction', label: 'nav.instruction', icon: 'spark' },
+      { to: '/upload', label: 'nav.brain', icon: 'brain' },
+      { to: '/brain', label: 'nav.instruction', icon: 'spark' },
       { to: '/schedule', label: 'nav.schedule', icon: 'calendar' },
       { to: '/results', label: 'nav.results', icon: 'layers' },
     ],