📋 Add alternatives/comparison page to documentation

Summary

Create a dedicated comparison page (docs/alternatives.md or docs/comparison.md) that provides an honest, detailed comparison of zae-limiter against other rate limiting solutions.

Why

• Users search for "X vs Y" comparisons before choosing a library
• SEO opportunity for "DynamoDB rate limiting vs Redis" searches
• Demonstrates domain expertise and builds trust
• Helps users make informed decisions

Proposed Content

Comparison Table

Note: Latency numbers are from actual benchmarks in docs/performance.md. zae-limiter uses DynamoDB TransactWriteItems which has inherent latency, but this is acceptable for LLM workloads where API calls are 100ms-10s+.

Detailed Comparisons

vs Redis-based rate limiters

• When to choose Redis: sub-millisecond latency required, high-frequency API rate limiting
• When to choose zae-limiter: LLM token budgets, hierarchical limits, post-hoc adjustment, AWS-native
• Migration considerations

vs API Gateway throttling

• When API Gateway is enough
• When you need application-level control

vs In-process rate limiters

• Single vs distributed deployments
• The coordination problem

When to use each

Flowchart or decision tree helping users pick the right tool.

Related

• #147 - "Is zae-limiter right for you?" section

Acceptance Criteria

• Comparison page created in docs
• Honest pros/cons for each alternative
• Links to specific alternative libraries/docs
• Decision flowchart or clear guidance
• Cross-linked from guide main page (#147)
• Latency numbers reference actual benchmarks from docs/performance.md

Create docs/alternatives.md or docs/comparison.md and start by reviewing docs/performance.md for the latency figures. Research and link the named alternatives, add the comparison guidance and decision flowchart, then cross-link the page from the guide main page referenced by #147. Done means all acceptance criteria are covered and claims are supported by specific documentation or benchmarks.