Fix WebSocket disconnect during large manual log file uploads (#1062)

[rquidute]

Summary

Fixes #1062: THCLI reports a WebSocket error after successfully uploading a manual test log (e.g. TC-CADMIN-1.17), even though the upload itself completed.

Root cause

ManualLogUploadStep.handle_uploaded_file() called logger.info() once per line of the uploaded file. Uploaded logs can have hundreds of thousands of lines (the reported log had ~191K). Each logger.info() call:

• gets picked up by TestLogHandler, batched, and broadcast over the same main WebSocket the CLI is using (TestUIObserver → socket_connection_manager.broadcast)
• triggers a blocking session.commit() in TestDBObserver

This flood of broadcast + DB-commit work stalls the event loop long enough (~100s in the reported log) that the WebSocket's ping/pong keepalive isn't serviced in time, and the connection gets dropped without a proper close handshake — ConnectionClosedError: no close frame received or sent. The CLI's very next action (sending the prompt response after upload) hits the broken socket and surfaces as Unexpected error uploading file: ..., even though the file was already uploaded successfully.

Fix

• Batch uploaded log lines into chunks of 500 before calling logger.info(), instead of one call per line — a large file now produces a handful of log/broadcast/DB-commit operations instead of hundreds of thousands.
• Collapse the invalid-UTF-8 warning to a single message per upload instead of one per bad line.
• Add app.uvicorn_worker.ExtendedTimeoutUvicornWorker, which raises ws_ping_timeout to 60s (matching the value already used by the dev-only start-reload.sh script), and wire it up as the default worker class in gunicorn/start.sh so production tolerates the same event-loop stalls as local dev.

Testing

• Added unit tests covering: chunked batching behavior + line-order integrity, invalid-UTF-8 replacement/single-warning behavior, and unsupported content-type rejection.
• Verified flake8/mypy/black/isort clean on the touched files.
• Verified the chunking logic directly against the module (bypassing an unrelated, pre-existing local env issue where the full pytest suite requires the matter SDK checkout module not present in this sandbox).

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[gemini-code-assist]

Code Review

This pull request addresses websocket connection drops during large manual log uploads (GitHub issue #1062) by batching log lines into chunks of 500 before logging them, and by extending the uvicorn worker's websocket ping timeout to 60 seconds. Feedback suggests using .rstrip("\r\n") instead of .rstrip("\n") to properly handle Windows-style line endings and avoid formatting issues.