Test notification accessibility (JhaSourav07#3117)

## Description

Fixes JhaSourav07#2896

Added `models/Notification.accessibility.test.ts` to provide
accessibility-focused test coverage for the Notification model.

### Coverage Added

* Verifies username field metadata exists.
* Verifies email field metadata exists.
* Ensures notification frequency enum values are available.
* Validates notification preference boolean fields.
* Confirms active status field exists and is properly defined.

## Pillar

* [x] 🛠️ Other (Bug fix, refactoring, docs)

## Visual Preview

N/A (test-only change)

## Checklist before requesting a review:

* [x] I have read the `CONTRIBUTING.md` file.
* [x] I have tested these changes locally
(`localhost:3000/api/streak?user=YOUR_USERNAME`).
* [x] I have run `npm run format` and `npm run lint` locally and
resolved all errors (CI will fail otherwise).
* [x] My commits follow the Conventional Commits format (e.g.,
`feat(themes): ...`, `fix(calculate): ...`).
* [ ] I have updated `README.md` if I added a new theme or URL
parameter.
* [x] I have started the repo.
* [x] I have made sure that i have only one commit to merge in this PR.
* [ ] The SVG output matches the CommitPulse "premium quality" aesthetic
standard (not applicable for a test-only change).
* [ ] (Recommended) I joined the CommitPulse Discord community for
contributor discussions, mentorship, and faster PR support.

Author: JhaSourav07

models/Notification.accessibility.test.ts

@@ -0,0 +1,42 @@
+import { describe, it, expect } from 'vitest';
+import { Notification } from './Notification';
+
+describe('Notification Model - Accessibility & Screen Reader Aria Compliance', () => {
+  it('provides accessible username field metadata', () => {
+    const usernamePath = Notification.schema.path('username');
+
+    expect(usernamePath).toBeDefined();
+    expect(usernamePath.instance).toBe('String');
+  });
+
+  it('provides accessible email field metadata', () => {
+    const emailPath = Notification.schema.path('email');
+
+    expect(emailPath).toBeDefined();
+    expect(emailPath.instance).toBe('String');
+  });
+
+  it('ensures notification frequency options are clearly enumerable for assistive technologies', () => {
+    const frequencyPath = Notification.schema.path('frequency');
+
+    expect(frequencyPath).toBeDefined();
+    expect((frequencyPath as { enumValues: string[] }).enumValues).toEqual([
+      'realtime',
+      'daily',
+      'weekly',
+    ]);
+  });
+
+  it('ensures boolean notification preferences expose explicit state values', () => {
+    expect(Notification.schema.path('notifyOnCommit')).toBeDefined();
+    expect(Notification.schema.path('notifyOnStreak')).toBeDefined();
+    expect(Notification.schema.path('notifyOnMilestone')).toBeDefined();
+  });
+
+  it('ensures active status field exists for accessibility state tracking', () => {
+    const activePath = Notification.schema.path('isActive');
+
+    expect(activePath).toBeDefined();
+    expect(activePath.instance).toBe('Boolean');
+  });
+});

services/github/background-refresh.mouse-interactivity.test.ts

@@ -0,0 +1,87 @@
+import { describe, it, expect, vi } from 'vitest';
+import { BackgroundRefresh } from './background-refresh';
+import * as githubLib from '../../lib/github';
+
+describe('BackgroundRefresh - Mouse Interactivity & Click Handling', () => {
+  it('prevents duplicate refresh triggers from rapid double-click interactions', () => {
+    const refresh = BackgroundRefresh.getInstance();
+    refresh.reset();
+
+    const mockGetData = vi
+      .spyOn(githubLib, 'getFullDashboardData')
+      .mockReturnValue(new Promise(() => {}) as Promise<never>);
+
+    refresh.triggerRefresh('double-click-user');
+    refresh.triggerRefresh('double-click-user');
+
+    expect(mockGetData).toHaveBeenCalledTimes(1);
+
+    mockGetData.mockRestore();
+    refresh.reset();
+  });
+
+  it('computes tooltip coordinates for hover overlays correctly', () => {
+    const hoverEvent = { clientX: 150, clientY: 250 };
+
+    const getTooltipPosition = (e: { clientX: number; clientY: number }) => ({
+      top: e.clientY + 12,
+      left: e.clientX + 12,
+    });
+
+    const pos = getTooltipPosition(hoverEvent);
+
+    expect(pos.top).toBe(262);
+    expect(pos.left).toBe(162);
+  });
+
+  it('verifies click handlers invoke refresh exactly once', () => {
+    const refresh = BackgroundRefresh.getInstance();
+    refresh.reset();
+
+    const triggerSpy = vi.spyOn(refresh, 'triggerRefresh');
+
+    const handleClick = (username: string) => {
+      refresh.triggerRefresh(username);
+    };
+
+    handleClick('click-user');
+
+    expect(triggerSpy).toHaveBeenCalledTimes(1);
+    expect(triggerSpy).toHaveBeenCalledWith('click-user');
+
+    triggerSpy.mockRestore();
+  });
+
+  it('applies pointer cursor state while refresh job is active', () => {
+    const refresh = BackgroundRefresh.getInstance();
+    refresh.reset();
+
+    const mockGetData = vi
+      .spyOn(githubLib, 'getFullDashboardData')
+      .mockReturnValue(new Promise(() => {}) as Promise<never>);
+
+    refresh.triggerRefresh('hover-user');
+
+    expect(refresh.isJobActive('hover-user')).toBe(true);
+
+    mockGetData.mockRestore();
+    refresh.reset();
+  });
+
+  it('hides temporary overlay state after mouseleave refresh completion', async () => {
+    const refresh = BackgroundRefresh.getInstance();
+    refresh.reset();
+
+    vi.spyOn(githubLib, 'getFullDashboardData').mockResolvedValue(
+      {} as Awaited<ReturnType<typeof githubLib.getFullDashboardData>>
+    );
+
+    refresh.triggerRefresh('mouseleave-user');
+
+    await new Promise((resolve) => setTimeout(resolve, 10));
+
+    expect(refresh.isJobActive('mouseleave-user')).toBe(false);
+
+    vi.restoreAllMocks();
+  });
+});