Initial scaffold: wages app

Full wage cost reporting app — weekly/monthly views, rolling 12-week/12-month
history, budget management, Workforce API sync with SSE backfill, net sales
via forecasting public API, department filter, CSV export.

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

frontend/src/components/AuthGate.tsx

@@ -0,0 +1,41 @@
+import { useEffect, useState, createContext, useContext } from 'react'
+import type { User } from '../types'
+
+interface AuthCtx { user: User }
+const Ctx = createContext<AuthCtx | null>(null)
+
+export function useAuth() {
+  const ctx = useContext(Ctx)
+  if (!ctx) throw new Error('useAuth must be used inside AuthGate')
+  return ctx
+}
+
+export default function AuthGate({ children }: { children: React.ReactNode }) {
+  const [user, setUser] = useState<User | null>(null)
+
+  useEffect(() => {
+    fetch('/wages/api/auth/verify?app=wages', { credentials: 'include' })
+      .then(r => {
+        if (!r.ok) {
+          ;(window.top ?? window).location.href = '/login'
+          return null
+        }
+        return r.json()
+      })
+      .then(data => { if (data) setUser(data) })
+      .catch(() => { ;(window.top ?? window).location.href = '/login' })
+  }, [])
+
+  if (!user) {
+    return (
+      <div style={{
+        display: 'flex', alignItems: 'center', justifyContent: 'center',
+        height: '100vh', color: '#6b7280',
+      }}>
+        Loading…
+      </div>
+    )
+  }
+
+  return <Ctx.Provider value={{ user }}>{children}</Ctx.Provider>
+}