refactor: 优化 NBPF 模块 - 缓存导入/合并重复方法/减少I/O

- crypto.py: 8个_imp_*方法改为_ModuleCache类缓存导入
- crypto.py: outer/inner加解密合并为_layer_encrypt/decrypt
- crypto.py: 提取公共摘要计算方法，拆分长方法
- compiler.py: 删除_obfuscate_code中未使用的死代码
- loader.py: 3次ZIP扫描合并为1次缓存读取
- format.py: 更新为使用_ModuleCache
- 合计减少205行代码（1707→1502）

system-monitor/main.py

@@ -113,8 +113,8 @@ def _collector_loop(interval: float = 5.0):
         try:
             stats = _collect_stats()
             _history.append(stats)
-        except Exception:
-            pass
+        except Exception as e:
+            print(f"[SystemMonitor] 监控数据采集错误: {e}")
         time.sleep(interval)
 
 
@@ -316,8 +316,8 @@ def _run_http_server(host: str, port: int):
     _http_server = server
     try:
         server.serve_forever()
-    except Exception:
-        pass
+    except Exception as e:
+        print(f"[SystemMonitor] 服务启动错误: {e}")
 
 
 # ── 生命周期 ──
@@ -368,8 +368,8 @@ def stop():
     if _http_server:
         try:
             _http_server.shutdown()
-        except Exception:
-            pass
+        except Exception as e:
+            print(f"[SystemMonitor] 服务停止错误: {e}")
         _http_server = None
 
     _history.clear()