test: add unit tests for email service, clients route, and ImpersonationBanner

- Email service: 16 tests covering buildConfirmationEmail and buildReminderEmail
  (recipient, subject, body content, groomer presence/absence, reminder timing)
- Clients route: 17 tests covering CRUD endpoints including validation,
  404 handling, soft-disable (disabledAt), and confirm-required delete
- ImpersonationBanner: 8 tests covering render, session expiry auto-end,
  Extend button visibility, and End/Audit button callbacks

Part of GRO-76 (Phase 1 unit/integration tests).

Co-Authored-By: Paperclip <noreply@paperclip.ing>

apps/web/src/__tests__/ImpersonationBanner.test.tsx

@@ -0,0 +1,154 @@
+import { describe, it, expect, vi, beforeEach, afterEach } from "vitest";
+import { render, screen, fireEvent, act } from "@testing-library/react";
+import { ImpersonationBanner } from "../portal/ImpersonationBanner.js";
+import type { ImpersonationSession } from "../portal/mockData.js";
+
+function makeSession(overrides: Partial<ImpersonationSession> = {}): ImpersonationSession {
+  const now = new Date();
+  const expires = new Date(now.getTime() + 30 * 60 * 1000); // 30 min from now
+  return {
+    active: true,
+    staffName: "Jordan",
+    staffRole: "manager",
+    customerName: "Sarah Mitchell",
+    reason: "Customer requested help",
+    startedAt: now.toISOString(),
+    expiresAt: expires.toISOString(),
+    extended: false,
+    readOnly: true,
+    auditLog: [],
+    ...overrides,
+  };
+}
+
+describe("ImpersonationBanner", () => {
+  const onEnd = vi.fn();
+  const onExtend = vi.fn();
+  const onShowAudit = vi.fn();
+
+  beforeEach(() => {
+    vi.clearAllMocks();
+    vi.useFakeTimers();
+  });
+
+  afterEach(() => {
+    vi.useRealTimers();
+  });
+
+  it("renders banner when session is active", () => {
+    render(
+      <ImpersonationBanner
+        session={makeSession()}
+        onEnd={onEnd}
+        onExtend={onExtend}
+        onShowAudit={onShowAudit}
+      />
+    );
+    expect(screen.getByText(/STAFF VIEW/)).toBeInTheDocument();
+  });
+
+  it("shows the customer name", () => {
+    render(
+      <ImpersonationBanner
+        session={makeSession()}
+        onEnd={onEnd}
+        onExtend={onExtend}
+        onShowAudit={onShowAudit}
+      />
+    );
+    expect(screen.getByText("Sarah Mitchell")).toBeInTheDocument();
+  });
+
+  it("returns null when session is not active", () => {
+    const { container } = render(
+      <ImpersonationBanner
+        session={makeSession({ active: false })}
+        onEnd={onEnd}
+        onExtend={onExtend}
+        onShowAudit={onShowAudit}
+      />
+    );
+    expect(container.firstChild).toBeNull();
+  });
+
+  it("calls onEnd when End Session is clicked", () => {
+    render(
+      <ImpersonationBanner
+        session={makeSession()}
+        onEnd={onEnd}
+        onExtend={onExtend}
+        onShowAudit={onShowAudit}
+      />
+    );
+    fireEvent.click(screen.getByRole("button", { name: /end session/i }));
+    expect(onEnd).toHaveBeenCalledTimes(1);
+  });
+
+  it("calls onShowAudit when Audit is clicked", () => {
+    render(
+      <ImpersonationBanner
+        session={makeSession()}
+        onEnd={onEnd}
+        onExtend={onExtend}
+        onShowAudit={onShowAudit}
+      />
+    );
+    fireEvent.click(screen.getByRole("button", { name: /audit/i }));
+    expect(onShowAudit).toHaveBeenCalledTimes(1);
+  });
+
+  it("calls onEnd automatically when session expires", async () => {
+    const expiredSoon = new Date(Date.now() + 500);
+    const session = makeSession({ expiresAt: expiredSoon.toISOString() });
+
+    render(
+      <ImpersonationBanner
+        session={session}
+        onEnd={onEnd}
+        onExtend={onExtend}
+        onShowAudit={onShowAudit}
+      />
+    );
+
+    // Advance past expiry
+    await act(async () => {
+      vi.advanceTimersByTime(2000);
+    });
+
+    expect(onEnd).toHaveBeenCalled();
+  });
+
+  it("shows Extend button when warning is active and session not yet extended", () => {
+    // Set expiry to 3 min from now — within warning threshold (< 5 min)
+    const expiresAt = new Date(Date.now() + 3 * 60 * 1000).toISOString();
+    render(
+      <ImpersonationBanner
+        session={makeSession({ expiresAt, extended: false })}
+        onEnd={onEnd}
+        onExtend={onExtend}
+        onShowAudit={onShowAudit}
+      />
+    );
+    // Tick the timer once to trigger showWarning
+    act(() => {
+      vi.advanceTimersByTime(1000);
+    });
+    expect(screen.getByRole("button", { name: /extend/i })).toBeInTheDocument();
+  });
+
+  it("does not show Extend button when already extended", () => {
+    const expiresAt = new Date(Date.now() + 3 * 60 * 1000).toISOString();
+    render(
+      <ImpersonationBanner
+        session={makeSession({ expiresAt, extended: true })}
+        onEnd={onEnd}
+        onExtend={onExtend}
+        onShowAudit={onShowAudit}
+      />
+    );
+    act(() => {
+      vi.advanceTimersByTime(1000);
+    });
+    expect(screen.queryByRole("button", { name: /extend/i })).not.toBeInTheDocument();
+  });
+});