Align the claude-sdk-python and claude-sdk-typescript demo integrations behind
the published quickstarts: move the @region markers used for doc snippet
extraction, add the state-streaming and weather-tool snippet files, and add
setup-doc content. Runtime alignment: the TS agent handlers consistently emit
text/event-stream; the streaming snippets emit a fresh STATE_SNAPSHOT per delta
and drop the undeclared partial-json dependency.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>