docs(swift): add UIKit store usage examples

Author: okwasniewski

docs/docs/docs/api-reference/swift.mdx

@@ -250,6 +250,81 @@ NavigationLink("Open React Native Screen") {
 
 ---
 
+## Brownie Store (UIKit)
+
+The `Store` class provides UIKit-friendly APIs for subscribing to state changes.
+
+### Closure-based subscription
+
+```swift
+import UIKit
+import Brownie
+
+class MyViewController: UIViewController {
+  private var store: Store<MyStoreState>?
+  private var cancelSubscription: (() -> Void)?
+
+  override func viewDidLoad() {
+    super.viewDidLoad()
+
+    store = StoreManager.get(key: MyStoreState.storeName, as: MyStoreState.self)
+
+    // Subscribe to all state changes
+    cancelSubscription = store?.subscribe { [weak self] state in
+      self?.updateUI(with: state)
+    }
+  }
+
+  deinit {
+    cancelSubscription?()
+  }
+}
+```
+
+### Subscribe to specific property
+
+```swift
+// Only fires when `counter` changes
+cancelSubscription = store?.subscribe(\.counter) { [weak self] counter in
+  self?.counterLabel.text = "Count: \(counter)"
+}
+```
+
+### Combine-based subscription
+
+```swift
+import Combine
+
+class MyViewController: UIViewController {
+  private var store: Store<MyStoreState>?
+  private var cancellables = Set<AnyCancellable>()
+
+  override func viewDidLoad() {
+    super.viewDidLoad()
+
+    store = StoreManager.get(key: MyStoreState.storeName, as: MyStoreState.self)
+
+    store?.$state
+      .sink { [weak self] state in
+        self?.updateUI(with: state)
+      }
+      .store(in: &cancellables)
+  }
+}
+```
+
+### Updating state
+
+```swift
+// Update with closure
+store?.set { $0.counter += 1 }
+
+// Update specific property
+store?.set(\.user.name, to: "New Name")
+```
+
+---
+
 ## Example
 
 You can find an example consumer Apple platform app [here](https://github.com/callstack/react-native-brownfield/tree/main/apps/AppleApp) and the consumed library module [here](https://github.com/callstack/react-native-brownfield/tree/main/apps/RNApp/ios).