Add CalendarClock icon, planner/settings capabilities

- backend/src/auth.js: extract caps from JWT (planner/settings), hasCap/requireCap
- backend/src/routes/config.js: gate categories + test-connection on requireCap('settings')
- frontend/src/types.ts: add caps[] to User, export can() helper
- frontend/src/App.tsx: gate /settings route on can(user, 'settings')
- frontend/src/components/Layout.tsx: gate nav item on can(user, 'settings')

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/App.tsx

@@ -3,6 +3,7 @@ import { AuthGate } from './components/AuthGate'
 import { Layout } from './components/Layout'
 import { Planner } from './pages/Planner'
 import { CategorySettings } from './pages/CategorySettings'
+import { can } from './types'
 import type { User } from './types'
 
 function AppRoutes({ user }: { user: User }) {
@@ -11,7 +12,7 @@ function AppRoutes({ user }: { user: User }) {
       <Routes>
         <Route path="/"         element={<Navigate to="/planner" replace />} />
         <Route path="/planner"  element={<Planner />} />
-        <Route path="/settings" element={user.is_admin ? <CategorySettings /> : <Navigate to="/planner" replace />} />
+        <Route path="/settings" element={can(user, 'settings') ? <CategorySettings /> : <Navigate to="/planner" replace />} />
         <Route path="*"         element={<Navigate to="/planner" replace />} />
       </Routes>
     </Layout>

frontend/src/components/Layout.tsx

@@ -1,5 +1,6 @@
 import { NavLink } from 'react-router-dom'
 import { CalendarClock, Settings, LogOut } from 'lucide-react'
+import { can } from '../types'
 import type { User } from '../types'
 
 interface Props {
@@ -30,7 +31,7 @@ export function Layout({ user, children }: Props) {
 
         <div style={{ flex: 1, padding: '0.5rem 0', overflowY: 'auto' }}>
           <NavItem to="/planner" icon={CalendarClock} label="Planner" />
-          {user.is_admin && <NavItem to="/settings" icon={Settings} label="Category Settings" />}
+          {can(user, 'settings') && <NavItem to="/settings" icon={Settings} label="Category Settings" />}
         </div>
 
         <div style={{ padding: '0.75rem 1rem', borderTop: '1px solid var(--surface-2)' }}>

frontend/src/types.ts

@@ -2,6 +2,11 @@ export interface User {
   email: string
   name: string
   is_admin: boolean
+  caps: string[]
+}
+
+export function can(user: User, cap: string): boolean {
+  return user.is_admin || user.caps.includes(cap)
 }
 
 export interface DayData {