Expand documentation wiki with guides and patterns

[RAprogramm]

Objective

Create comprehensive wiki documentation to help users migrate, integrate, and follow best practices with masterror.

Background

Phase 1.4 from KaiCode 2026 preparation (#205). While core documentation (REQUIREMENTS.md, CONTRIBUTING.md, ARCHITECTURE.md) is complete, extended guides would improve user onboarding and adoption.

Tasks

Migration Guides

• Migration from thiserror
• Migration from anyhow
• Migration guide comparison table
• Breaking changes checklist

Best Practices

• Error hierarchy design patterns
• Metadata attachment guidelines
• Redaction policy recommendations
• Performance optimization tips
• Testing error paths strategies

Common Usage Patterns

• HTTP service error handling (REST APIs)
• gRPC service error handling
• Database error integration patterns
• External API client error handling
• Async/tokio integration patterns

Integration Examples

• Axum framework integration
• Actix-web framework integration
• Tonic gRPC integration
• SQLx database integration
• Multi-transport example (HTTP + gRPC)

Location

docs/wiki/ directory or GitHub Wiki

Success Criteria

• At least 4 migration guides published
• Best practices document covers 5+ scenarios
• Common patterns documented with code examples
• Integration examples compile and run
• All examples include tests

Priority

Low (can be done incrementally)

Related

• Prepare repository for KaiCode 2026 competition #205 KaiCode 2026 preparation