## Documentation Infrastructure & Service Implementation Guide
This PR introduces documentation tooling and contributor resources to help maintain and expand the SelfHostBlocks project:
### Service Implementation Guide
- Add comprehensive guide for implementing new SHB services
- Covers contracts, testing, documentation, and integration patterns
- Provides step-by-step instructions and best practices for contributors
### Redirect Management Tool
- Add automated update-redirects tool to maintain documentation links
- Extracts heading IDs from markdown files across docs/, modules/, demo/
- Maps source files to target HTML pages using project routing logic
- Generates missing redirects in format expected by nixos-render-docs
