feat(email): add SMTP security modes (starttls/ssl/none) with sensible default ports; add /notify_test endpoint; support ALWAYS_NOTIFY_ON_STARTUP to force first-run notification

chore(docker): run enhanced_crawler.py as entrypoint

ops(compose): load env via env_file and remove hardcoded secrets

docs: update README and .env.template for SMTP and startup notification

Dockerfile

@@ -32,5 +32,5 @@ HEALTHCHECK --interval=30s --timeout=10s --start-period=5s --retries=3 \
 # 暴露端口（用於健康檢查 API）
 EXPOSE 8080
 
-# 執行爬蟲
-CMD ["python", "crawler.py"]
+# 執行爬蟲主程式
+CMD ["python", "enhanced_crawler.py"]