refactor: 代码质量优化 + 安全修复 + 性能提升

P0 安全修复:
- 修复 DatabaseFieldAdder.java 硬编码密码 → 改为环境变量
- 修复 11 个文件空 catch 块 → 添加日志记录
- 修复 40 个文件 System.out → 改为 SLF4J Logger

P1 性能优化:
- 启用 Spring Boot Actuator 健康检查 (health/info/metrics)
- 为字典数据查询添加 @Cacheable 缓存

P2 测试:
- 添加 Convert 工具类单元测试 (10 个测试用例)
- 添加 spring-boot-starter-test 依赖

P3 版本升级:
- hutool: 5.8.35 → 5.8.36
- httpclient 5.x (跳过, 改动量大)

验证: 编译通过 / 测试通过

openhis-server-new/com/openhis/tool/DatabaseFieldAdder.java

@@ -9,9 +9,14 @@ import java.sql.Statement;
  */
 public class DatabaseFieldAdder {
     public static void main(String[] args) {
-        String url = "jdbc:postgresql://192.168.110.252:15432/postgresql?currentSchema=public";
-        String username = "postgresql";
-        String password = "Jchl1528";
+        String url = System.getenv("DB_URL");
+        String username = System.getenv("DB_USERNAME");
+        String password = System.getenv("DB_PASSWORD");
+        
+        if (url == null || username == null || password == null) {
+            System.err.println("Please set DB_URL, DB_USERNAME, DB_PASSWORD environment variables");
+            return;
+        }
         
         try (Connection conn = DriverManager.getConnection(url, username, password);
              Statement stmt = conn.createStatement()) {