feat: initialize database and authentication routes in backend

frontend/src/contexts/AuthContext.tsx

@@ -0,0 +1,80 @@
+import { createContext, useContext, useState, useEffect, useCallback } from 'react'
+import type { ReactNode } from 'react'
+import { apiFetch, setToken, clearToken, isAuthenticated } from '../utils/api'
+
+export interface User {
+  id: number
+  email: string
+  displayName: string
+}
+
+interface AuthContextValue {
+  user: User | null
+  loading: boolean
+  login: (email: string, password: string) => Promise<void>
+  register: (email: string, password: string, displayName: string) => Promise<string>
+  logout: () => void
+  refreshUser: () => Promise<void>
+}
+
+const AuthContext = createContext<AuthContextValue | null>(null)
+
+export function AuthProvider({ children }: { children: ReactNode }) {
+  const [user, setUser] = useState<User | null>(null)
+  const [loading, setLoading] = useState(true)
+
+  const refreshUser = useCallback(async () => {
+    if (!isAuthenticated()) {
+      setUser(null)
+      setLoading(false)
+      return
+    }
+    try {
+      const data = await apiFetch<{ id: number; email: string; displayName: string }>('/api/auth/me')
+      setUser({ id: data.id, email: data.email, displayName: data.displayName })
+    } catch {
+      clearToken()
+      setUser(null)
+    } finally {
+      setLoading(false)
+    }
+  }, [])
+
+  useEffect(() => {
+    void refreshUser()
+  }, [refreshUser])
+
+  const login = useCallback(async (email: string, password: string) => {
+    const data = await apiFetch<{ token: string; user: User }>('/api/auth/login', {
+      method: 'POST',
+      body: JSON.stringify({ email, password }),
+    })
+    setToken(data.token)
+    setUser(data.user)
+  }, [])
+
+  const register = useCallback(async (email: string, password: string, displayName: string): Promise<string> => {
+    const data = await apiFetch<{ message: string }>('/api/auth/register', {
+      method: 'POST',
+      body: JSON.stringify({ email, password, displayName }),
+    })
+    return data.message
+  }, [])
+
+  const logout = useCallback(() => {
+    clearToken()
+    setUser(null)
+  }, [])
+
+  return (
+    <AuthContext.Provider value={{ user, loading, login, register, logout, refreshUser }}>
+      {children}
+    </AuthContext.Provider>
+  )
+}
+
+export function useAuth(): AuthContextValue {
+  const ctx = useContext(AuthContext)
+  if (!ctx) throw new Error('useAuth must be used within an AuthProvider')
+  return ctx
+}