Debusine: live log streaming

Debusine currently only shows task logs after a task has fully completed. This means developers working with long-running jobs (such as package builds or test pipelines) have no way to monitor progress in real time or catch failures early. This project adds live log streaming to Debusine. The implementation follows a four-stage pipeline. On the worker side, the sub-process runner will be extended to capture stdout and stderr incrementally as a task runs, sending each line to the server over the existing WebSocket connection rather than waiting for the task to finish. On the server side, a handler will receive these lines and write them to a per-task Redis Stream, providing a persistent, ordered, low-latency buffer that supports multiple simultaneous readers. A server-side view will then expose these log lines to browser clients via Server-Sent Events or a WebSocket endpoint. As a stretch goal, the Debusine web UI will subscribe to that endpoint and display lines appearing on the task page in real time, with no page refresh required. Deliverables: - Worker-side incremental log capture and WebSocket emission, with full test coverage - Server-side Redis Stream ingestion, per-task key namespacing, and post-task flush to PostgreSQL - A server view that streams log lines to browser clients for running tasks - A browser-side UI update that shows live output on the task detail page using plain JavaScript, without any frontend framework