重构 SwiftUI 页面

Use the Build iOS Apps plugin and its SwiftUI view refactor skill to clean up [NameOfScreen.swift] without changing what the screen does or how it looks.

Constraints:
- Preserve behavior, layout, navigation, and business logic unless you find a bug that must be called out separately.
- Default to MV, not MVVM. Prefer `@State`, `@Environment`, `@Query`, `.task`, `.task(id:)`, and `onChange` before introducing a new view model, and only keep a view model if this feature clearly needs one.
- Reorder the view so stored properties, computed state, `init`, `body`, view helpers, and helper methods are easy to scan top to bottom.
- Extract meaningful sections into dedicated `View` types with small explicit inputs, `@Binding`s, and callbacks. Do not replace one giant `body` with a pile of large computed `some View` properties.
- Move non-trivial button actions and side effects out of `body` into small methods, and move real business logic into services or models.
- Keep the root view tree stable. Avoid top-level `if/else` branches that swap entirely different screens when localized conditional sections or modifiers are enough.
- Fix Observation ownership while refactoring: use `@State` for root `@Observable` models on iOS 17+, and avoid optional or delayed-initialized view models unless the UI genuinely needs that state shape.
- After each extraction, run the smallest useful build or test check that proves the screen still behaves the same.

Deliver:
- the refactored screen and any extracted subviews
- a short explanation of the new subview boundaries and data flow
- any places where you intentionally kept a view model and why
- the validation checks you ran to prove behavior stayed intact