feat(common): 添加 BusinessException/GlobalExceptionHandler/CompanyContext/状态枚举 (T007/T008/T012-T015)

src/main/java/com/label/common/context/CompanyContext.java

@@ -0,0 +1,21 @@
+package com.label.common.context;
+
+public class CompanyContext {
+    private static final ThreadLocal<Long> COMPANY_ID = new ThreadLocal<>();
+
+    public static void set(Long companyId) {
+        COMPANY_ID.set(companyId);
+    }
+
+    public static Long get() {
+        return COMPANY_ID.get();
+    }
+
+    public static void clear() {
+        COMPANY_ID.remove();  // Use remove() not set(null) to prevent memory leaks
+    }
+
+    private CompanyContext() {  // Prevent instantiation
+        throw new UnsupportedOperationException("Utility class");
+    }
+}