test(resume-parser): add massive-scaling test suite (JhaSourav07#2874) (JhaSourav07#3004)

## Description

Adds the comprehensive `resume-parser.massive-scaling.test.ts` test
suite to verify the performance, bounds validation, and execution speed
under massive scaling conditions. This includes handling 2,000+ distinct
skills, 500+ education/experience items, and exactly 5MB maximum file
size inputs.

Fixes JhaSourav07#2874

## Pillar

- [ ] 🎨 Pillar 1 — New Theme Design
- [ ] 📐 Pillar 2 — Geometric SVG Improvement
- [ ] 🕐 Pillar 3 — Timezone Logic Optimization
- [x] 🛠️ Other (Bug fix, refactoring, docs)

## Visual Preview

N/A (Utility/Unit Tests only)

## 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.
- [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.
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standard.
- [ ] (Recommended) I joined the CommitPulse Discord community.

Author: boss477

lib/resume-parser.massive-scaling.test.ts

@@ -0,0 +1,73 @@
+import { describe, it, expect } from 'vitest';
+import { parseResume, MAX_FILE_SIZE } from './resume-parser';
+
+describe('resume-parser-massive-scaling', () => {
+  it('should parse 2,000 distinct skills efficiently without performance degradation', async () => {
+    const skillsList = Array.from({ length: 2000 }, (_, i) => `SkillName${i}`);
+    const text = `John Doe\nSkills\n${skillsList.join(', ')}`;
+    const buffer = Buffer.from(text);
+
+    const startTime = Date.now();
+    const result = await parseResume(buffer, 'application/pdf');
+    const duration = Date.now() - startTime;
+
+    expect(duration).toBeLessThan(500); // completed within 500ms
+    expect(result.skills.length).toBe(2000);
+    expect(result.skills[0]).toBe('SkillName0');
+    expect(result.skills[1999]).toBe('SkillName1999');
+  });
+
+  it('should handle a large number of education entries (500 entries) correctly', async () => {
+    const educationLines: string[] = [];
+    for (let i = 0; i < 500; i++) {
+      educationLines.push(`University Number ${i} 2010 - 2014`);
+    }
+    const text = `John Doe\nEducation\n${educationLines.join('\n')}`;
+    const buffer = Buffer.from(text);
+
+    const startTime = Date.now();
+    const result = await parseResume(buffer, 'application/pdf');
+    const duration = Date.now() - startTime;
+
+    expect(duration).toBeLessThan(1000);
+    expect(result.education.length).toBe(500);
+    expect(result.education[0].institution).toBe('University Number 0 2010 - 2014');
+    expect(result.education[499].institution).toBe('University Number 499 2010 - 2014');
+  });
+
+  it('should handle a large number of experience entries (500 entries) correctly', async () => {
+    const experienceLines: string[] = [];
+    for (let i = 0; i < 500; i++) {
+      experienceLines.push(`Company Name ${i} 2015 to 2019`);
+    }
+    const text = `John Doe\nExperience\n${experienceLines.join('\n')}`;
+    const buffer = Buffer.from(text);
+
+    const startTime = Date.now();
+    const result = await parseResume(buffer, 'application/pdf');
+    const duration = Date.now() - startTime;
+
+    expect(duration).toBeLessThan(1000);
+    expect(result.experience.length).toBe(500);
+    expect(result.experience[0].company).toBe('Company Name 0 2015 to 2019');
+    expect(result.experience[499].company).toBe('Company Name 499 2015 to 2019');
+  });
+
+  it('should process a file matching exactly the maximum allowed file size boundary (5MB) without crashing', async () => {
+    // Generate a 5MB string with a valid name, email and some text
+    const header = 'John Doe\njohn.doe@example.com\n';
+    const fillSize = MAX_FILE_SIZE - Buffer.byteLength(header);
+    const filler = 'A'.repeat(fillSize);
+    const buffer = Buffer.from(header + filler);
+
+    expect(buffer.byteLength).toBe(MAX_FILE_SIZE);
+
+    const startTime = Date.now();
+    const result = await parseResume(buffer, 'application/pdf');
+    const duration = Date.now() - startTime;
+
+    expect(duration).toBeLessThan(2000); // 5MB parsed in under 2 seconds
+    expect(result.name).toBe('John Doe');
+    expect(result.email).toBe('john.doe@example.com');
+  });
+});