Faster, Smoother Media Capture and Drawing

🔄 Improvements

• Video and presentation frames now appear immediately while uploading, with a clear "Uploading..." state Screenshot
• Drawing capture now continues smoothly to live video or available slides after attaching an annotation

🛠 Fixes

• Fixed: Video pauses while drawing, keeping annotations aligned with the captured frame
• Fixed: Multiple video frames or slides can now be attached in quick succession without waiting for previous uploads to finish