feat: implement email sending functionality via Resend service

app/hooks/use-send-permission.ts

@@ -0,0 +1,52 @@
+import { useState, useEffect } from 'react'
+
+interface SendPermissionResponse {
+  canSend: boolean
+  error?: string
+  remainingEmails?: number
+}
+
+export function useSendPermission() {
+  const [canSend, setCanSend] = useState(false)
+  const [loading, setLoading] = useState(false)
+  const [error, setError] = useState<string | null>(null)
+  const [remainingEmails, setRemainingEmails] = useState<number | undefined>()
+
+  const checkPermission = async () => {
+    setLoading(true)
+    setError(null)
+    
+    try {
+      const response = await fetch('/api/emails/send-permission')
+      
+      if (!response.ok) {
+        throw new Error('权限检查失败')
+      }
+
+      const data = await response.json() as SendPermissionResponse
+      setCanSend(data.canSend)
+      setRemainingEmails(data.remainingEmails)
+      
+      if (!data.canSend && data.error) {
+        setError(data.error)
+      }
+    } catch (err) {
+      setCanSend(false)
+      setError(err instanceof Error ? err.message : '权限检查失败')
+    } finally {
+      setLoading(false)
+    }
+  }
+
+  useEffect(() => {
+    checkPermission()
+  }, [])
+
+  return {
+    canSend,
+    loading,
+    error,
+    remainingEmails,
+    checkPermission
+  }
+}