feat: add AI email extraction with Cloudflare Workers AI

Add AI-powered email content extraction feature using Cloudflare Workers AI to automatically identify and extract important information from emails including verification codes, authentication links, service links, and subscription links.

Features:
- AI extraction with priority-based logic (auth_code > auth_link > service_link > subscription_link > other_link)
- Admin allowlist configuration with wildcard support (*@example.com)
- Frontend display in both email list (compact) and detail view (full mode)
- Bilingual documentation (Chinese/English)
- Database migration: add metadata field to raw_mails (v0.0.3 -> v0.0.4)

Technical highlights:
- Proper regex escaping for wildcard pattern matching
- Content truncation to avoid AI token limits
- Error handling that won't affect email receiving
- JSON schema validation for AI responses
- Type-safe TypeScript implementation
- Vue I18n support with special character escaping

References:
- Inspired by Alle Project: https://github.com/bestruirui/Alle
- Uses Cloudflare Workers AI JSON Mode

🤖 Generated with Claude Code
Co-Authored-By: Claude <noreply@anthropic.com>

vitepress-docs/docs/.vitepress/en.ts

@@ -142,6 +142,7 @@ function sidebarGuide(): DefaultTheme.SidebarItem[] {
             text: 'Additional Features',
             collapsed: false,
             items: [
+                { text: 'AI Email Recognition', link: 'feature/ai-extract' },
                 { text: 'Configure SMTP IMAP Proxy', link: 'feature/config-smtp-proxy' },
                 { text: 'Send Email API', link: 'feature/send-mail-api' },
                 { text: 'View Email API', link: 'feature/mail-api' },

vitepress-docs/docs/.vitepress/zh.ts

@@ -142,6 +142,7 @@ function sidebarGuide(): DefaultTheme.SidebarItem[] {
             text: '附加功能',
             collapsed: false,
             items: [
+                { text: 'AI 邮件识别', link: 'feature/ai-extract' },
                 { text: '配置 SMTP IMAP 代理服务', link: 'feature/config-smtp-proxy' },
                 { text: '发送邮件 API', link: 'feature/send-mail-api' },
                 { text: '查看邮件 API', link: 'feature/mail-api' },