feat: add iOS Live Photo export native module

AVAssetWriter pipeline generating 3s MOV at 30fps with
Apple content identifier metadata and still-image-time.
HEIC generation with maker note pairing. PHAssetCreation
with photo + pairedVideo resources. CIFilter-based effects
for Ken Burns, Color Shift, Vignette, and Glitch.

modules/livephoto-ios/ios/LivePhotoModule.swift

@@ -0,0 +1,82 @@
+import ExpoModulesCore
+import Photos
+import PhotosUI
+
+public class LivePhotoModule: Module {
+  public func definition() -> ModuleDefinition {
+    Name("LivePhoto")
+
+    /// Generate a Live Photo from an image + animation config and save to photo library.
+    /// Returns the local identifier of the saved PHAsset.
+    AsyncFunction("exportLivePhoto") { (configJson: String, promise: Promise) in
+      guard let data = configJson.data(using: .utf8),
+            let config = try? JSONSerialization.jsonObject(with: data) as? [String: Any],
+            let sourceUri = config["sourceUri"] as? String else {
+        promise.reject("INVALID_CONFIG", "Invalid wallpaper config JSON")
+        return
+      }
+
+      let shaderId = config["animation"] as? String ?? "ken-burns"
+      let uniforms = config["uniforms"] as? [String: Double] ?? [:]
+      let intensity = Float(uniforms["intensity"] ?? 0.5)
+      let speed = Float(uniforms["speed"] ?? 0.3)
+      let direction = Float(uniforms["direction"] ?? 0.0)
+
+      // Resolve image path
+      let imagePath: String
+      if sourceUri.hasPrefix("file://") {
+        imagePath = String(sourceUri.dropFirst(7))
+      } else {
+        imagePath = sourceUri
+      }
+
+      guard let image = UIImage(contentsOfFile: imagePath) else {
+        promise.reject("IMAGE_NOT_FOUND", "Could not load image at \(imagePath)")
+        return
+      }
+
+      let screenSize = UIScreen.main.bounds.size
+      let scale = UIScreen.main.scale
+      let targetSize = CGSize(width: screenSize.width * scale, height: screenSize.height * scale)
+
+      Task {
+        do {
+          let exporter = LivePhotoExporter()
+          let assetId = try await exporter.export(
+            image: image,
+            targetSize: targetSize,
+            shaderId: shaderId,
+            intensity: intensity,
+            speed: speed,
+            direction: direction
+          )
+          promise.resolve(assetId)
+        } catch {
+          promise.reject("EXPORT_FAILED", error.localizedDescription)
+        }
+      }
+    }
+
+    /// Check if the photo library is accessible.
+    AsyncFunction("checkPermission") { () -> String in
+      let status = PHPhotoLibrary.authorizationStatus(for: .readWrite)
+      switch status {
+      case .authorized, .limited: return "granted"
+      case .denied, .restricted: return "denied"
+      case .notDetermined: return "undetermined"
+      @unknown default: return "unknown"
+      }
+    }
+
+    /// Request photo library write permission.
+    AsyncFunction("requestPermission") { (promise: Promise) in
+      PHPhotoLibrary.requestAuthorization(for: .readWrite) { status in
+        switch status {
+        case .authorized, .limited: promise.resolve("granted")
+        case .denied, .restricted: promise.resolve("denied")
+        default: promise.resolve("denied")
+        }
+      }
+    }
+  }
+}