fix(serial-console): decode binary WebSocket frames as UTF-8

[cjp256]

The on_message callback passed WebSocket messages directly to PC.print, which forwards to Python's built-in print(). Per RFC 6455, the websocket-client library delivers text-opcode frames as str and binary-opcode frames as bytes. When the server sends a binary frame, print() renders the bytes via repr() — emitting literals like b'\x1b[0;32m OK \xe2\x80\xa6\r\r\n' instead of interpreting ANSI escapes and UTF-8.

The Azure Serial Console stream is semantically text (a guest TTY), but the client shouldn't rely on the server's choice of opcode. Decode bytes/bytearray messages as UTF-8 (with errors="replace") before printing so the terminal renders colors, box-drawing characters, and line endings correctly regardless of which opcode the server uses.

---

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Related command

az serial-console connect -n $name -g $rg

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[azure-client-tools-bot-prd]

️✔️Azure CLI Extensions Breaking Change Test

️✔️Non Breaking Changes

[yonzhan]

Thank you for your contribution! We will review the pull request and get back to you soon.

[github-actions]

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[Copilot]

Pull request overview

This PR improves az serial-console connect output rendering by ensuring WebSocket binary frames are decoded to UTF-8 before being printed, so ANSI escapes and multi-byte characters display correctly even when the server uses a binary opcode.

Changes:

• Bump the serial-console extension version to 1.0.0b4 and add a matching HISTORY entry.
• Add _decode_ws_message and use it in the WebSocket on_message handler to decode bytes/bytearray as UTF-8 with errors="replace".
• Add unit tests covering decoding behavior for str, bytes, bytearray, ANSI escapes, UTF-8 box-drawing characters, and invalid UTF-8 replacement.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
src/serial-console/setup.py	Version bump to publish the fix as 1.0.0b4.
src/serial-console/azext_serialconsole/custom.py	Decode binary WebSocket payloads to UTF-8 before printing to the terminal.
src/serial-console/azext_serialconsole/tests/latest/test_decode_ws_message.py	Adds unit coverage for the decoding helper.
src/serial-console/HISTORY.rst	Documents the rendering fix in release notes.

[yonzhan]

Please fix CI issues

[necusjz]

/azp run

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