feat: add tenant and user management with migrations, handlers, and tests

- Implemented tenant and user management features including:
  - Tenant creation and management with associated migrations.
  - User creation and management with associated migrations.
  - Tenant membership management with associated migrations.
  - Platform user roles management with associated migrations.
  - Quota management with associated migrations.
  - Article and template management with associated migrations.
- Added HTTP handlers for templates and workspaces.
- Created tests for protected and public routes.
- Introduced a script to check tenant scope in SQL queries.
- Documented task plan for backend completion and frontend foundation.

server/internal/tenant/domain/article.go

@@ -0,0 +1,15 @@
+package domain
+
+import "time"
+
+type Article struct {
+	ID               int64
+	TenantID         int64
+	SourceType       string
+	TemplateID       *int64
+	CurrentVersionID *int64
+	GenerateStatus   string
+	PublishStatus    string
+	CreatedAt        time.Time
+	UpdatedAt        time.Time
+}