feat: Add 10 comprehensive Node.js interview questions

[heysaiyad]

Summary

Added 10 new in-depth Node.js interview questions covering advanced topics that were missing from the existing collection.

New Questions Added

1. Event Loop Working - Six phases, microtasks vs macrotasks
2. Streams and Buffers - Four stream types, backpressure handling
3. Cluster vs Worker Threads - Comparison and use cases
4. Memory Leak Debugging - Common causes and debugging tools
5. Middleware Pattern - Express middleware types and examples
6. Async Patterns - Callbacks, Promises, Async/Await comparison
7. Security Best Practices - SQL injection, XSS, authentication
8. Performance Optimization - Caching, clustering, compression
9. Testing Async Code - Jest, Mocha patterns for async testing
10. NPM Package Security - Auditing, lock files, CI/CD security

Changes

• Added 10 new .md files in src/data/question-groups/nodejs/content/
• Total Node.js questions: 8 → 18
• Fixed compression middleware example in performance-optimization.md

Testing

• Verified all files render correctly on local dev server
• Checked markdown formatting and code syntax

[Copilot]

Pull request overview

This PR adds ten new in-depth Node.js interview content files, expanding coverage into advanced topics such as the event loop, async patterns, performance, security, and testing.

Changes:

• Added detailed markdown content on advanced Node.js internals (event loop, clusters vs worker threads, memory leaks, async patterns).
• Added practical guides for operational topics (streams & buffers, performance optimization, security best practices, npm package security).
• Added testing-focused content including async testing patterns in Jest and Mocha, HTTP endpoint testing, mocking, timers, and event emitters.

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 8 comments.

Show a summary per file

File	Description
src/data/question-groups/nodejs/content/testing-async-code.md	Documents Jest/Mocha patterns, mocking, timers, event emitters, HTTP endpoint testing, and common async testing pitfalls.
src/data/question-groups/nodejs/content/streams-and-buffers.md	Explains Node.js streams and buffers with examples for types of streams, backpressure handling, and buffer manipulation.
src/data/question-groups/nodejs/content/security-best-practices.md	Covers SQL/NoSQL injection, XSS, headers, rate limiting, auth, input validation, env vars, HTTPS, and a security checklist.
src/data/question-groups/nodejs/content/performance-optimization.md	Provides patterns for avoiding event loop blocking, caching, DB query optimization, streaming, pooling, compression, clustering, JSON handling, and monitoring.
src/data/question-groups/nodejs/content/npm-package-security.md	Describes npm audit, lockfiles, automated updates, semver, detecting malicious packages, private registries, overrides, CI checks, and cleanup of unused deps.
src/data/question-groups/nodejs/content/middleware-pattern.md	Explains Express-style middleware types, common middleware (auth, logging, rate limiting), execution order, and best practices.
src/data/question-groups/nodejs/content/memory-leak-debugging.md	Introduces common Node.js memory leak sources, detection patterns, and debugging tools like inspector, heap snapshots, and clinic.
src/data/question-groups/nodejs/content/event-loop-working.md	Describes the six event loop phases, microtasks vs macrotasks, and usage of process.nextTick vs setImmediate with best practices.
src/data/question-groups/nodejs/content/cluster-vs-worker-threads.md	Compares cluster vs worker threads, with examples, use cases, shared memory, and best practices.
src/data/question-groups/nodejs/content/async-patterns.md	Surveys callbacks, promises, async/await, parallel vs sequential execution, Promise utilities, error handling, and common async pitfalls.

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[heysaiyad]

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