Implement batch upload functionality and enhance upload result tracking

[miguelmarcondesf]

Blog Post Context

This PR implements the batch async upload strategy as the second approach in the concurrency control series. This builds upon the
sequential baseline to demonstrate parallel processing with Promise.all() and provides real-world performance analysis.

What This PR Implements

Batch Async Upload Algorithm (O(3) theoretical, O(n/k) practical)

For 1,000 files upload:

• Phase 1: All MD5 hash generation in parallel (1,000 files × Promise.all)
• Phase 2: All pre-signed URL generation in parallel (1,000 files × Promise.all)
• Phase 3: All file uploads in parallel (1,000 files × Promise.all)
• Total: 3 parallel phases instead of 3,000 sequential operations

Performance Comparison Infrastructure

• Real-time performance tracking table
• Automatic percentage improvement calculation
• Side-by-side strategy comparison in single UI

Key Files Added/Modified

  src/useCases/useAsyncBatchUpload.ts // Batch async algorithm implementation
  src/App.tsx // Dual-strategy UI with performance table
  README.md // Updated with algorithm comparison & bottleneck analysis

[Copilot]

Pull Request Overview

This PR implements a batch async upload strategy to demonstrate parallel processing performance improvements over sequential uploads. The implementation includes a complete UI for comparing upload strategies with real-time performance tracking and comprehensive documentation updates.

• Adds batch async upload algorithm using Promise.all() for parallel processing
• Implements dual-strategy UI with radio button selection and performance comparison table
• Updates documentation with usage instructions and troubleshooting guide

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 4 comments.

File	Description
src/useCases/useAsyncBatchUpload.ts	New batch upload hook implementing 3-phase parallel processing algorithm
src/App.tsx	Enhanced UI with strategy selection, performance tracking table, and dual-hook integration
README.md	Updated documentation with usage instructions, troubleshooting section, and architecture changes