Modal adds WebSocket support for real-time apps

Modal now supports WebSocket connections, letting functions on its platform maintain persistent, bidirectional links between client and server instead of per-request HTTP connections. Each WebSocket connection counts as a single input, so functions not bound by CPU/GPU should allow concurrent inputs or Modal spins up a new container per connection. Modal auto-scales WebSocket handlers, targeting real-time streaming, progress updates on long-running tasks, and hosting frameworks like ComfyUI, Streamlit and Gradio.