feat(ios): skip already-processed shares in getSharedImageData (Phase 1E)

Return nil from getSharedImageData() when the current sharedPhotoShareId
equals the stored sharedPhotoProcessedShareId, so a share that was already
marked processed is no longer re-imported on subsequent app activations.

The check runs before reading the image file and logs
"[ShareTarget] shareId=<id> already processed; skipping". It leaves the
image file and all metadata intact (cleanup is deferred to a later phase),
and does not change behavior for brand-new shares. iOS only; no changes to
markProcessed(), the Share Extension, Android, or the JS flow.

ios/App/App/SharedImageUtility.swift

@@ -62,6 +62,19 @@ public class SharedImageUtility {
         
         let fileName = userDefaults.string(forKey: sharedPhotoFileNameKey) ?? "shared-image.jpg"
         let shareId = userDefaults.string(forKey: sharedPhotoShareIdKey)
+
+        // Phase 1E: skip a share that has already been marked processed.
+        // If the current pending shareId matches the processed marker, treat it
+        // as if no pending share exists. Leave the file and metadata intact -
+        // cleanup is deferred to a later phase.
+        let processedShareId = userDefaults.string(forKey: sharedPhotoProcessedShareIdKey)
+        if let shareId = shareId,
+           let processedShareId = processedShareId,
+           shareId == processedShareId {
+            print("[ShareTarget] shareId=\(shareId) already processed; skipping")
+            return nil
+        }
+
         let fileURL = containerURL.appendingPathComponent(filePath)
 
         // Read image data from file