Add benchmark results to README and documentation

[AbianS]

Summary

Add benchmark results and performance metrics to the README and documentation site to showcase Rustrak's performance characteristics.

Motivation

Rustrak already has a comprehensive benchmarking suite (packages/benchmarks/) that produces detailed performance metrics. However, these results are not visible to potential users evaluating the project. Publishing real benchmark data would:

• Demonstrate the "lightweight" and "fast" claims with concrete numbers
• Help users understand expected performance for capacity planning
• Build trust through transparency
• Differentiate Rustrak from heavier alternatives

Proposed Solution

1. Add Performance section to README.md

Add a "Performance" section after "Why Rustrak?" with key metrics:

## Performance

Benchmarked on [hardware specs], [Rustrak version]:

| Metric | Value |
|--------|-------|
| Throughput | X,XXX events/second |
| P50 Latency | X.X ms |
| P99 Latency | XX.X ms |
| Memory (idle) | XX MB |
| Memory (peak @ 1k rps) | XXX MB |
| Docker Image | ~20 MB |

2. Add detailed benchmark page to documentation

Create a dedicated benchmarks page in apps/docs/ with:

• Methodology (scenarios, hardware, configuration)
• Detailed results for each scenario (baseline, burst, sustained, stress)
• Comparison charts
• Instructions to reproduce benchmarks

3. Consider CI automation (optional)

• Run benchmarks on release tags
• Auto-update benchmark results in docs
• Track performance regressions

Files to Update

• README.md - Add performance summary section
• apps/docs/ - Create detailed benchmark documentation page
• Potentially packages/benchmarks/results/ - Add reference baseline results

Additional Context

The benchmark suite already supports:

• Multiple scenarios (baseline, burst, sustained, stress)
• Latency histograms (P50/P95/P99)
• Memory and CPU metrics via Docker
• JSON output for comparison
• Result comparison tooling

See packages/benchmarks/README.md for full benchmark documentation.