Docs: Add comprehensive documentation for result builders

- Expand Scene protocol docs with overview, conformance guide, topics
- Add SceneBuilder docs with usage example and explanation
- Add ButtonRowBuilder docs with control flow support details
- Add RadioButtonGroupBuilder docs with usage example
- Add StatusBarItemBuilder docs with See Also references

All result builders now have consistent, DocC-compatible documentation
explaining their purpose, usage patterns, and supported control flow.

Sources/TUIkit/App/Scene.swift

@@ -4,10 +4,41 @@
 //  Created by LAYERED.work
 //  License: MIT
 
-/// The base protocol for scenes in TUIkit.
+/// The base protocol for scenes in TUIKit.
 ///
-/// A scene represents a part of the app structure,
-/// typically a window or a group of views.
+/// A scene represents a distinct region of the app's user interface,
+/// analogous to SwiftUI's `Scene` protocol. In TUIKit, scenes define
+/// the top-level structure of your terminal application.
+///
+/// ## Overview
+///
+/// Scenes sit between the ``App`` and ``View`` layers in TUIKit's
+/// architecture. While views define the content, scenes define how
+/// that content is organized at the application level.
+///
+/// Currently, TUIKit provides one scene type:
+/// - ``WindowGroup``: Displays content in the terminal window
+///
+/// ## Conforming to Scene
+///
+/// You typically don't create custom scene types. Instead, use the
+/// built-in ``WindowGroup`` in your app's `body`:
+///
+/// ```swift
+/// @main
+/// struct MyApp: App {
+///     var body: some Scene {
+///         WindowGroup {
+///             ContentView()
+///         }
+///     }
+/// }
+/// ```
+///
+/// ## Topics
+///
+/// ### Built-in Scenes
+/// - ``WindowGroup``
 @MainActor
 public protocol Scene {}
 
@@ -38,11 +69,35 @@ public struct WindowGroup<Content: View>: Scene {
 
 // MARK: - SceneBuilder
 
-/// A result builder for scene hierarchies.
+/// A result builder that constructs scene hierarchies from closures.
+///
+/// `SceneBuilder` enables the declarative syntax used in ``App/body-swift.property``
+/// to define your application's scene structure. You don't use this type directly;
+/// instead, the `@SceneBuilder` attribute is applied to the `body` property of
+/// your ``App`` conforming type.
+///
+/// ## Overview
+///
+/// When you write:
+///
+/// ```swift
+/// var body: some Scene {
+///     WindowGroup {
+///         ContentView()
+///     }
+/// }
+/// ```
+///
+/// The `@SceneBuilder` attribute transforms this closure into a scene that
+/// TUIKit can render. Currently, `SceneBuilder` supports a single scene
+/// in the body, which is typically a ``WindowGroup``.
 @MainActor
 @resultBuilder
 public struct SceneBuilder {
-    /// Builds a single scene.
+    /// Builds a scene expression from a single scene component.
+    ///
+    /// - Parameter content: The scene to build.
+    /// - Returns: The same scene, unchanged.
     public static func buildBlock<Content: Scene>(_ content: Content) -> Content {
         content
     }

Sources/TUIkit/StatusBar/StatusBarItem.swift

@@ -604,7 +604,40 @@ public extension SystemStatusBarItem {
 
 // MARK: - Status Bar Item Builder
 
-/// Result builder for creating status bar items.
+/// A result builder that constructs arrays of status bar items.
+///
+/// `StatusBarItemBuilder` enables the declarative syntax for defining multiple
+/// items in a status bar. You don't use this type directly; instead, the
+/// `@StatusBarItemBuilder` attribute is applied to closures that define
+/// status bar content.
+///
+/// ## Overview
+///
+/// When you write:
+///
+/// ```swift
+/// .statusBarItems {
+///     StatusBarItem(shortcut: .arrowsUpDown, label: "navigate")
+///     StatusBarItem(shortcut: .enter, label: "select", key: .enter)
+///     StatusBarItem(shortcut: .escape, label: "back") { goBack() }
+/// }
+/// ```
+///
+/// The `@StatusBarItemBuilder` attribute transforms this closure into an array
+/// of ``StatusBarItemProtocol`` conforming items that the status bar can display.
+///
+/// ## Supported Control Flow
+///
+/// The builder supports:
+/// - Multiple item expressions
+/// - `if`/`else` conditionals
+/// - `if let` optional binding
+/// - `for`...`in` loops
+///
+/// ## See Also
+///
+/// - ``StatusBarItem``
+/// - ``View/statusBarItems(_:)``
 @resultBuilder
 public struct StatusBarItemBuilder {
 }

Sources/TUIkit/Views/ButtonRow.swift

@@ -39,7 +39,34 @@ public struct ButtonRow: View {
 
 // MARK: - ButtonRow Builder
 
-/// Result builder for creating button rows.
+/// A result builder that constructs arrays of buttons for use in ``ButtonRow``.
+///
+/// `ButtonRowBuilder` enables the declarative syntax for defining multiple
+/// buttons within a ``ButtonRow``. You don't use this type directly; instead,
+/// the `@ButtonRowBuilder` attribute is applied to the trailing closure of
+/// ``ButtonRow/init(spacing:_:)``.
+///
+/// ## Overview
+///
+/// When you write:
+///
+/// ```swift
+/// ButtonRow {
+///     Button("Cancel", style: .plain) { dismiss() }
+///     Button("OK", style: .primary) { confirm() }
+/// }
+/// ```
+///
+/// The `@ButtonRowBuilder` attribute transforms this closure into an array
+/// of ``Button`` instances that the row can lay out horizontally.
+///
+/// ## Supported Control Flow
+///
+/// The builder supports:
+/// - Multiple button expressions
+/// - `if`/`else` conditionals
+/// - `if let` optional binding
+/// - `for`...`in` loops
 @resultBuilder
 public struct ButtonRowBuilder {
     /// Combines multiple buttons into a single array.

Sources/TUIkit/Views/RadioButton.swift

@@ -60,7 +60,35 @@ public struct RadioButtonItem<Value: Hashable> {
 
 // MARK: - Radio Button Group Builder
 
-/// Result builder for radio button items.
+/// A result builder that constructs arrays of radio button items for use in ``RadioButtonGroup``.
+///
+/// `RadioButtonGroupBuilder` enables the declarative syntax for defining multiple
+/// options within a ``RadioButtonGroup``. You don't use this type directly; instead,
+/// the `@RadioButtonGroupBuilder` attribute is applied to the trailing closure of
+/// ``RadioButtonGroup/init(selection:orientation:_:)``.
+///
+/// ## Overview
+///
+/// When you write:
+///
+/// ```swift
+/// RadioButtonGroup(selection: $choice) {
+///     RadioButtonItem(.option1, "First Option")
+///     RadioButtonItem(.option2, "Second Option")
+///     RadioButtonItem(.option3, "Third Option")
+/// }
+/// ```
+///
+/// The `@RadioButtonGroupBuilder` attribute transforms this closure into an array
+/// of ``RadioButtonItem`` instances that the group can render and manage.
+///
+/// ## Supported Control Flow
+///
+/// The builder supports:
+/// - Multiple item expressions
+/// - `if`/`else` conditionals
+/// - `if let` optional binding
+/// - `for`...`in` loops
 @resultBuilder
 public enum RadioButtonGroupBuilder<Value: Hashable> {
     public static func buildBlock(_ items: RadioButtonItem<Value>...) -> [RadioButtonItem<Value>] {