fix: omit user stream market filter for all markets

[cesarenaldi]

Summary

• Omit the user stream markets filter when subscribing to all markets
• Keep narrowed user stream subscriptions sending markets: [...]
• Update protocol and manager tests for the all-market frame shape

Verification

• uv run pytest tests/unit/test_streams_user_protocol.py tests/unit/test_streams_user_manager.py tests/unit/test_streams_user_events.py -q
• uv run ruff format --check .
• uv run ruff check .
• uv run pyright
• uv run pytest -q

Notes

• Compared with the TypeScript SDK. Its user stream builder currently appears to send markets: [] for broad subscriptions too, so the same behavior likely needs a follow-up there.

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Note

Low Risk
Small WebSocket protocol shape change with focused tests; risk is mainly if a server required markets: [] rather than a missing field.

Overview
Fixes the CLOB user WebSocket initial subscribe frame when the client wants all markets: it no longer sends markets: [] and instead omits the markets field entirely. Narrow subscriptions are unchanged and still send markets with the explicit market list.

build_initial_frame in user_protocol.py gates markets on include_all_markets. Unit and manager tests were updated to expect no markets key for broad subscriptions (including all-markets demotion/promotion flows).

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