v1.0.18

Release v1.0.18 with Web Worker crypto offloading, WebRTC Safari/iOS compatibility improvements, backpressure flow control, upload/download error handling, and UI enhancements.

Key changes:

• feat(workers): offload file crypto to web workers
• feat(ui): add active transfer warning banner
• fix(webrtc): improve safari compat and protect metadata privacy
• fix(upload): implement pull flow control for backpressure
• perf(upload): replace busy polling with event-driven backpressure
• fix: add iOS size limit and upload error handling
• fix(download): various Safari/iOS auto-download and user gesture fixes
• fix: validate complete decrypted file size and empty stream detection
• fix(cli): adjust qr code terminal output, remove query params from session request