refactor: migrate Search to injected ownership and typed routes

[kunihir0]

Summary

• Inject Search dependencies and give SearchView stable ViewModel ownership.
• Replace AnyView destinations with typed Search routes.
• Add explicit Search states and correlated presentation events.
• Add the minimal prepared-runtime AppScope required by Search.

Validation

• 56 targeted tests passed.
• 416 full tests passed.
• Signed iOS 15.4 build passed.
• Changed-file SwiftLint passed.
• Code review: APPROVE.
• Architecture review: CLEAR.