test(quota-monitor): add coverage for GitHub API quota tracking and rate limit handling (JhaSourav07#3151)

## Description
This PR introduces a comprehensive test suite for
services/github/quota-monitor.ts to validate quota tracking, rate limit
header parsing, refresh accounting, low-quota detection, and reset
window handling.

## Changes Made

1.Added

services/github/quota-monitor.test.ts

2. Test Coverage

The new test suite includes 5 test cases:

- Validates parsing of standard GitHub X-RateLimit-* response headers.
- Verifies correct tracking of remaining API credits.
- Ensures low-quota detection triggers when remaining requests fall
below the configured threshold.
- Confirms refresh operations are counted accurately.
- Validates reset timestamps are converted from seconds to milliseconds
correctly.


Fixes JhaSourav07#2295 

## Pillar

- [x] 📐 Pillar 2 — Geometric SVG Improvement
- [x] 🛠️ Other (Bug fix, refactoring, docs)


## 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): ...`).
- [x] 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.
- [x] The SVG output matches the CommitPulse "premium quality" aesthetic
standard (no raw elements, smooth animations, correct fonts).
- [x] (Recommended) I joined the CommitPulse Discord community for
contributor discussions, mentorship, and faster PR support.

Author: JhaSourav07

services/github/quota-monitor.test.ts

@@ -0,0 +1,59 @@
+import { describe, it, expect, beforeEach } from 'vitest';
+import { QuotaMonitor } from './quota-monitor';
+
+describe('QuotaMonitor', () => {
+  let monitor: QuotaMonitor;
+
+  beforeEach(() => {
+    monitor = QuotaMonitor.getInstance();
+    monitor.reset();
+  });
+
+  it('parses X-RateLimit headers correctly', () => {
+    monitor.updateQuotaFromHeaders({
+      'x-ratelimit-limit': '5000',
+      'x-ratelimit-remaining': '4200',
+      'x-ratelimit-reset': '1710000000',
+    });
+
+    const quota = monitor.getQuota();
+
+    expect(quota.limit).toBe(5000);
+    expect(quota.remaining).toBe(4200);
+  });
+
+  it('calculates remaining API credits correctly', () => {
+    monitor.setQuota(5000, 1234, Date.now());
+
+    const quota = monitor.getQuota();
+
+    expect(quota.limit).toBe(5000);
+    expect(quota.remaining).toBe(1234);
+  });
+
+  it('flags quota as low when remaining credits are below 10%', () => {
+    monitor.setQuota(5000, 499, Date.now());
+
+    expect(monitor.isQuotaLow()).toBe(true);
+
+    monitor.setQuota(5000, 500, Date.now());
+
+    expect(monitor.isQuotaLow()).toBe(false);
+  });
+
+  it('tracks refresh operations correctly', () => {
+    monitor.incrementRefreshCount();
+    monitor.incrementRefreshCount();
+    monitor.incrementRefreshCount();
+
+    expect(monitor.getQuota().totalRefreshes).toBe(3);
+  });
+
+  it('parses reset window timestamps into milliseconds', () => {
+    monitor.updateQuotaFromHeaders({
+      'x-ratelimit-reset': '1710000000',
+    });
+
+    expect(monitor.getQuota().resetTime).toBe(1710000000 * 1000);
+  });
+});