feat: 完成B端认证系统和商户管理模块测试补全

主要变更：
- 新增B端认证系统（后台+H5）：登录、登出、Token刷新、密码修改
- 完善商户管理和商户账号管理功能
- 补全单元测试（ShopService: 72.5%, ShopAccountService: 79.8%）
- 新增集成测试（商户管理+商户账号管理）
- 归档OpenSpec提案（add-shop-account-management, implement-b-end-auth-system）
- 完善文档（使用指南、API文档、认证架构说明）

测试统计：
- 13个测试套件，37个测试用例，100%通过率
- 平均覆盖率76.2%，达标

OpenSpec验证：通过（strict模式）

internal/routes/h5.go

@@ -0,0 +1,68 @@
+package routes
+
+import (
+	"github.com/gofiber/fiber/v2"
+
+	"github.com/break/junhong_cmp_fiber/internal/bootstrap"
+	"github.com/break/junhong_cmp_fiber/internal/model"
+	"github.com/break/junhong_cmp_fiber/pkg/openapi"
+)
+
+// RegisterH5Routes 注册H5相关路由
+func RegisterH5Routes(router fiber.Router, handlers *bootstrap.Handlers, middlewares *bootstrap.Middlewares, doc *openapi.Generator, basePath string) {
+	if handlers.H5Auth != nil {
+		registerH5AuthRoutes(router, handlers.H5Auth, middlewares.H5Auth, doc, basePath)
+	}
+}
+
+func registerH5AuthRoutes(router fiber.Router, handler interface{}, authMiddleware fiber.Handler, doc *openapi.Generator, basePath string) {
+	h := handler.(interface {
+		Login(c *fiber.Ctx) error
+		Logout(c *fiber.Ctx) error
+		RefreshToken(c *fiber.Ctx) error
+		GetMe(c *fiber.Ctx) error
+		ChangePassword(c *fiber.Ctx) error
+	})
+
+	Register(router, doc, basePath, "POST", "/login", h.Login, RouteSpec{
+		Summary: "H5 登录",
+		Tags:    []string{"H5 认证"},
+		Input:   new(model.LoginRequest),
+		Output:  new(model.LoginResponse),
+		Auth:    false,
+	})
+
+	Register(router, doc, basePath, "POST", "/refresh-token", h.RefreshToken, RouteSpec{
+		Summary: "刷新 Token",
+		Tags:    []string{"H5 认证"},
+		Input:   new(model.RefreshTokenRequest),
+		Output:  new(model.RefreshTokenResponse),
+		Auth:    false,
+	})
+
+	authGroup := router.Group("", authMiddleware)
+
+	Register(authGroup, doc, basePath, "POST", "/logout", h.Logout, RouteSpec{
+		Summary: "登出",
+		Tags:    []string{"H5 认证"},
+		Input:   nil,
+		Output:  nil,
+		Auth:    true,
+	})
+
+	Register(authGroup, doc, basePath, "GET", "/me", h.GetMe, RouteSpec{
+		Summary: "获取当前用户信息",
+		Tags:    []string{"H5 认证"},
+		Input:   nil,
+		Output:  new(model.UserInfo),
+		Auth:    true,
+	})
+
+	Register(authGroup, doc, basePath, "PUT", "/password", h.ChangePassword, RouteSpec{
+		Summary: "修改密码",
+		Tags:    []string{"H5 认证"},
+		Input:   new(model.ChangePasswordRequest),
+		Output:  nil,
+		Auth:    true,
+	})
+}