test(BrandParticles-timezone-boundaries): verify Timezone Normalizati… (JhaSourav07#3526)

## Description

Fixes JhaSourav07#2650

## Pillar

- [x] 🕐 Pillar 3 — Timezone Logic Optimization

## Visual Preview

N/A (Test file addition)

## Checklist before requesting a review:

- [x] I have read the `CONTRIBUTING.md` file.
- [x] I have tested these changes locally.
- [x] I have run `npm run format` and `npm run lint` locally and
resolved all errors.
- [x] My commits follow the Conventional Commits format
(`test(BrandParticles-timezone-boundaries): verify Timezone
Normalization & Calendar Data Boundary Alignment`).
- [x] I have made sure that I have only one commit to merge in this PR.

Author: JhaSourav07

components/BrandParticles.timezone-boundaries.test.tsx

@@ -0,0 +1,128 @@
+import React from 'react';
+import { render, screen } from '@testing-library/react';
+import { beforeEach, afterEach, describe, expect, it, vi } from 'vitest';
+import BrandParticles from './BrandParticles';
+
+// Mock framer-motion to control particles rendering and inspect attributes
+vi.mock('framer-motion', () => ({
+  motion: {
+    div: ({
+      animate,
+      transition,
+      style,
+      ...props
+    }: {
+      animate?: unknown;
+      transition?: unknown;
+      style?: React.CSSProperties;
+      [key: string]: unknown;
+    }) => (
+      <div
+        {...props}
+        style={style}
+        data-testid="motion-div"
+        data-animate={JSON.stringify(animate)}
+        data-transition={JSON.stringify(transition)}
+      />
+    ),
+  },
+  useReducedMotion: () => false,
+}));
+
+describe('BrandParticles - Timezone Boundaries & Calendar Alignment', () => {
+  beforeEach(() => {
+    vi.restoreAllMocks();
+  });
+
+  afterEach(() => {
+    vi.unstubAllGlobals();
+  });
+
+  // --- Test Case 1 ---
+  it('renders successfully across multiple timezone offsets (UTC, EST, IST, JST)', () => {
+    const timezones = [0, 300, -330, -540]; // Offsets in minutes
+
+    timezones.forEach((offset) => {
+      vi.spyOn(Date.prototype, 'getTimezoneOffset').mockReturnValue(offset);
+      const { unmount } = render(<BrandParticles />);
+
+      const particles = screen.getAllByTestId('motion-div');
+      expect(particles).toHaveLength(40);
+
+      unmount();
+      vi.restoreAllMocks();
+    });
+  });
+
+  // --- Test Case 2 ---
+  it('renders correctly under leap year boundary system clocks', () => {
+    vi.useFakeTimers();
+    vi.setSystemTime(new Date('2024-02-29T23:59:59Z')); // Leap day rollover
+
+    render(<BrandParticles />);
+    const particles = screen.getAllByTestId('motion-div');
+    expect(particles).toHaveLength(40);
+
+    vi.useRealTimers();
+  });
+
+  // --- Test Case 3 ---
+  it('retains visual animation paths during Daylight Saving Time (DST) transitions', () => {
+    vi.useFakeTimers();
+    // Simulate spring forward transition
+    vi.setSystemTime(new Date('2026-03-08T02:00:00Z'));
+
+    render(<BrandParticles />);
+    const particles = screen.getAllByTestId('motion-div');
+    expect(particles).toHaveLength(40);
+
+    // Verify visual animate parameters are generated and valid
+    const firstParticle = particles[0];
+    const animateAttr = firstParticle.getAttribute('data-animate');
+    expect(animateAttr).toContain('y');
+    expect(animateAttr).toContain('x');
+    expect(animateAttr).toContain('rotate');
+
+    vi.useRealTimers();
+  });
+
+  // --- Test Case 4 ---
+  it('validates calendar date format utility stubs do not impact layout mounting tree', () => {
+    // Mock standard DateTimeFormat to emulate locale-specific changes
+    const mockDateTimeFormat = function () {
+      return {
+        format: () => '01/01/2026',
+        resolvedOptions: () =>
+          ({ locale: 'en-US', timeZone: 'UTC' }) as Intl.ResolvedDateTimeFormatOptions,
+      };
+    } as unknown as typeof Intl.DateTimeFormat;
+
+    vi.stubGlobal('Intl', {
+      ...Intl,
+      DateTimeFormat: mockDateTimeFormat,
+    });
+
+    render(<BrandParticles />);
+    const particles = screen.getAllByTestId('motion-div');
+    expect(particles).toHaveLength(40);
+
+    vi.unstubAllGlobals();
+  });
+
+  // --- Test Case 5 ---
+  it('remains visual-stable and aligned when timezone offset shifts dynamically', () => {
+    // Start with EST offset
+    const offsetSpy = vi.spyOn(Date.prototype, 'getTimezoneOffset').mockReturnValue(300);
+    const { rerender } = render(<BrandParticles />);
+
+    let particles = screen.getAllByTestId('motion-div');
+    expect(particles).toHaveLength(40);
+
+    // Shift to JST offset dynamically
+    offsetSpy.mockReturnValue(-540);
+    rerender(<BrandParticles />);
+
+    particles = screen.getAllByTestId('motion-div');
+    expect(particles).toHaveLength(40);
+  });
+});