refactor: modularize project structure and separate API from crawlers

- Introduce app/ package with config, services (storage, notifications), API server, and crawler modules
- Add BaseCrawler and BarronsCrawler; extract notifications and storage
- Keep enhanced_crawler.py as back-compat entry delegating to app.runner
- Add template crawler for future sites
- Update README with new structure and usage
- Extend .env.template with DATA_DIR/LOG_DIR options

.env.template

@@ -18,3 +18,8 @@ WEBHOOK_URL=https://hooks.slack.com/services/YOUR/SLACK/WEBHOOK
 
 # Discord Webhook（可選）
 DISCORD_WEBHOOK=https://discord.com/api/webhooks/YOUR/DISCORD/WEBHOOK
+
+# 進階（可選）：自訂資料與日誌目錄
+# 預設 Docker 會使用 /app/data、/app/logs；本機則使用 ./data、./logs
+# DATA_DIR=./data
+# LOG_DIR=./logs