docs: add README (#18)

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: 2sem

README.md

@@ -0,0 +1,137 @@
+# GADManager
+
+A Swift library for managing Google Mobile Ads with time-based throttling and lifecycle management.
+
+## Requirements
+
+- iOS 12.0+
+- Swift 5.10+
+
+## Installation
+
+### Swift Package Manager
+
+```swift
+.package(url: "https://github.com/2sem/GADManager.git", from: "1.4.0")
+```
+
+## Setup
+
+Add your ad unit IDs to `Info.plist` under the key `GADUnitIdentifiers` as a `[String: String]` dictionary:
+
+```xml
+<key>GADUnitIdentifiers</key>
+<dict>
+    <key>interstitial</key>
+    <string>ca-app-pub-xxxx/xxxx</string>
+    <key>opening</key>
+    <string>ca-app-pub-xxxx/xxxx</string>
+    <key>rewarded</key>
+    <string>ca-app-pub-xxxx/xxxx</string>
+</dict>
+```
+
+Define an enum for your ad units:
+
+```swift
+enum AdUnit: String {
+    case interstitial
+    case opening
+    case rewarded
+}
+```
+
+## Usage
+
+### Initialization
+
+```swift
+let adManager = GADManager<AdUnit>(window)
+adManager.delegate = self
+```
+
+### Interstitial
+
+```swift
+// Prepare (load)
+adManager.prepare(interstitialUnit: .interstitial, interval: 60 * 60)
+
+// Show
+adManager.show(unit: .interstitial) { unit, _, shown in
+    // shown: true if ad was displayed and dismissed
+}
+```
+
+### App Open
+
+```swift
+adManager.prepare(openingUnit: .opening)
+
+adManager.show(unit: .opening, needToWait: true) { unit, _, shown in }
+```
+
+### Rewarded
+
+```swift
+adManager.prepare(rewardUnit: .rewarded)
+
+adManager.show(unit: .rewarded) { unit, obj, rewarded in
+    if rewarded, let reward = obj as? GoogleMobileAds.AdReward {
+        print("Earned \(reward.amount) \(reward.type)")
+    }
+}
+```
+
+### Banner
+
+```swift
+if let bannerView = adManager.prepare(bannerUnit: .banner) {
+    bannerView.rootViewController = self
+    view.addSubview(bannerView)
+    bannerView.load(GoogleMobileAds.Request())
+}
+```
+
+### ATT Permission
+
+```swift
+if #available(iOS 14, *) {
+    adManager.requestPermission { status in
+        // load ads after permission resolved
+    }
+}
+```
+
+## Delegate
+
+```swift
+extension MyClass: GADManagerDelegate {
+    // Required: persist last shown time per unit
+    func GAD<E>(manager: GADManager<E>, lastShownTimeForUnit unit: E) -> Date {
+        return UserDefaults.standard.object(forKey: unit.rawValue) as? Date ?? .distantPast
+    }
+
+    func GAD<E>(manager: GADManager<E>, updatShownTimeForUnit unit: E, showTime time: Date) {
+        UserDefaults.standard.set(time, forKey: unit.rawValue)
+    }
+
+    // Optional
+    func GAD<E>(manager: GADManager<E>, didEarnRewardForUnit unit: E, reward: GoogleMobileAds.AdReward) {
+        print("Reward earned: \(reward.amount) \(reward.type)")
+    }
+
+    func GAD<E>(manager: GADManager<E>, willPresentADForUnit unit: E) {}
+    func GAD<E>(manager: GADManager<E>, didDismissADForUnit unit: E) {}
+}
+```
+
+## Timing
+
+| Constant | Default | Description |
+|---|---|---|
+| `defaultInterval` | 1 hour | Minimum time between interstitial/opening shows |
+| `opeingExpireInterval` | 4 hours (5 min DEBUG) | App Open ad validity after loading |
+
+## License
+
+MIT