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>

worker/src/constants.ts

@@ -3,7 +3,7 @@ export const CONSTANTS = {
 
     // DB Version
     DB_VERSION_KEY: 'db_version',
-    DB_VERSION: "v0.0.3",
+    DB_VERSION: "v0.0.4",
 
     // DB settings
     ADDRESS_BLOCK_LIST_KEY: 'address_block_list',
@@ -16,6 +16,7 @@ export const CONSTANTS = {
     EMAIL_RULE_SETTINGS_KEY: 'email_rule_settings',
     ROLE_ADDRESS_CONFIG_KEY: 'role_address_config',
     IP_BLACKLIST_SETTINGS_KEY: 'ip_blacklist_settings',
+    AI_EXTRACT_SETTINGS_KEY: 'ai_extract_settings',
 
     // KV
     TG_KV_PREFIX: "temp-mail-telegram",