Poly v0.2.1 Stateful interpreter, HTTP streaming

Major Changes:

Poly is now stateful - interpreter persists between invoke calls
Added HTTP streaming primitives: http_stream_start, http_stream_poll, http_stream_close
New Ollama Chat example app with live streaming support
Streaming Features:

Real-time typewriter effect for AI responses
Separate thinking/reasoning display (Ollama's new think format)
Session-based streaming with proper cleanup
Interpreter Improvements:

create_interpreter(), init_interpreter(), call_function() API
Hot reload reinitializes interpreter on .poly file changes
Fixed Alpine.js double-injection issue
Bug Fixes:

Session ID precision issue (JS safe integer range)
Double message send prevention
Proper error handling in stream polling