Release lock for interruptable client requests

[mishushakov]

fixes #213

[cursor]

PR Summary

Medium Risk
Changes execution streaming behavior and adds server-side kernel interruption via Jupyter REST API on disconnect; mistakes could interrupt valid runs or add extra traffic, but scope is contained to messaging/streaming.

Overview
Client disconnects now actively stop kernel execution. During streaming, the server periodically emits keepalive messages and, if the request task is cancelled (disconnect), calls the Jupyter POST /api/kernels/{id}/interrupt endpoint (via httpx) to interrupt the current kernel run and free the context for later executions.

Adds regression tests in JS and Python (sync/async) that simulate a timed-out client run followed by a successful subsequent execution, plus a changeset bump for @e2b/code-interpreter-template.

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[jakubno]

I don't think this is a correct fix. The executions in jupyter are in serial. What you would need to do here is to interrupt the execution on client disconnect

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

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