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/migrations/20260331100030_create_task_records.up.sql

@@ -0,0 +1,14 @@
+CREATE TABLE task_records (
+    id            BIGSERIAL PRIMARY KEY,
+    tenant_id     BIGINT NOT NULL REFERENCES tenants(id),
+    task_type     VARCHAR(50) NOT NULL,
+    resource_type VARCHAR(50) NOT NULL,
+    resource_id   BIGINT NOT NULL,
+    status        VARCHAR(20) NOT NULL DEFAULT 'pending',
+    retry_count   INT NOT NULL DEFAULT 0,
+    task_batch_id VARCHAR(100),
+    error_message TEXT,
+    created_at    TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    updated_at    TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);
+CREATE INDEX idx_task_record_status_type ON task_records(status, task_type);