feat(contact): Controller、Router 与 Wire 集成

- controller/contact_controller.go: 全部 17 个 REST API 端点处理器
- router.go: Contact 模块路由注册（JWT 中间件保护）
- provider.go: Wire Provider Set（DAO + Service + Controller）
- 更新全局 provider、wire.go、router.go 集成 Contact 模块

Made-with: Cursor

backend/go-service/app/contact/provider.go

@@ -0,0 +1,16 @@
+package contact
+
+import (
+	"github.com/echochat/backend/app/contact/controller"
+	"github.com/echochat/backend/app/contact/dao"
+	"github.com/echochat/backend/app/contact/service"
+	"github.com/google/wire"
+)
+
+// ContactSet Contact 模块依赖注入 Provider Set
+var ContactSet = wire.NewSet(
+	dao.NewFriendshipDAO,
+	dao.NewFriendGroupDAO,
+	service.NewContactService,
+	controller.NewContactController,
+)