feat: PostgreSQL withTenant-Helper und ClickHouse-Client

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/server/db/tenant.test.ts

@@ -0,0 +1,36 @@
+import { describe, it, expect, vi, beforeEach } from 'vitest'
+
+vi.mock('./client', () => ({
+  db: {
+    execute: vi.fn(),
+    query: vi.fn().mockResolvedValue([{ id: '1' }]),
+  },
+}))
+
+import { withTenant } from './tenant'
+import { db } from './client'
+
+describe('withTenant', () => {
+  beforeEach(() => vi.clearAllMocks())
+
+  it('setzt search_path auf tenant-Schema', async () => {
+    await withTenant('abc123', () => db.query('SELECT 1', []))
+    expect(db.execute).toHaveBeenCalledWith('SET search_path = tenant_abc123, public')
+  })
+
+  it('setzt search_path zurück auf public nach Ausführung', async () => {
+    await withTenant('abc123', () => db.query('SELECT 1', []))
+    expect(db.execute).toHaveBeenLastCalledWith('SET search_path = public')
+  })
+
+  it('setzt search_path zurück auch bei Fehler', async () => {
+    const fn = vi.fn().mockRejectedValue(new Error('DB-Fehler'))
+    await expect(withTenant('abc123', fn)).rejects.toThrow('DB-Fehler')
+    expect(db.execute).toHaveBeenLastCalledWith('SET search_path = public')
+  })
+
+  it('gibt Rückgabewert der Funktion zurück', async () => {
+    const result = await withTenant('abc123', async () => 'testdata')
+    expect(result).toBe('testdata')
+  })
+})