fix: restore camera media URL callback timing - #385

Summary

• Restore didCaptureMediaURL callback timing so it is not invoked from UIImagePickerController.dismiss completion
• Keep the camera picker dismiss call single to avoid the duplicate dismiss issue
• Preserve the successful-copy-only callback behavior

Verification

• ruby -e ... callback timing regression check: callback timing OK
• git diff --check
• git diff --cached --check
• xcodebuild -workspace Example/TLPhotoPicker.xcworkspace -scheme TLPhotoPicker -destination 'generic/platform=iOS Simulator' build