[ghzhost]

Summary

• Wires the tested and hook into , enabling real-time debounced filtering of contacts by name and address (fixes ContactBook's SearchBar and useContactSearch are fully implemented and tested but never wired into ContactBook #27).
• Replaces unvalidated inline inputs with the full component (which includes Stellar address format validation and name validation) (fixes ContactBook's actually-rendered add-contact form has zero address validation; the validated AddContact.tsx component is unused #19).
• Adds integration unit tests in verifying search filtering, contact addition, and contact removal.

Resolves #27 and #19.