Fail-soft on unknown template ids + map template 358 (AccountRmsUpdates)

[aktiwers]

Fixes #66.

The order plant floods the logs with ERROR tracebacks (Unknown template ID: 358) when Rithmic pushes a message type the library does not map. This PR has two parts that stand independently.

1. Fail-soft on unmapped template ids

BasePlant._convert_bytes_to_response raised Exception(f"Unknown template ID: {template_id}") for any template id missing from TEMPLATES_MAP. That exception is caught by the read/process loop and logged via logger.exception(...), so a single recurring unmapped message type produces a full traceback for every message and drowns out real errors.

It now:

• warns once per template id (dedupe set on the plant instance) and returns None,
• and the read loops (_process_loop in background_task_mixin.py and the inline loop in _send_and_recv_immediate) skip a None response and continue.

This half is safe regardless of what template 358 actually is — it just stops one unhandled message type from flooding the logs.

2. Map template 358 → AccountRmsUpdates

account_rms_updates_pb2.AccountRmsUpdates is already vendored in protocol_buffers/ but was never registered in TEMPLATES_MAP. This adds:

• 358: pb.account_rms_updates_pb2.AccountRmsUpdates to TEMPLATES_MAP,
• a dispatch branch in OrderPlant._process_response firing a new on_account_rms_update client event, mirroring how on_bracket_update (353) is wired.

On the 358 == AccountRmsUpdates mapping: this is verified circumstantially, not from an official Rithmic spec. On a live Rithmic paper session the template-358 frames decode cleanly against AccountRmsUpdates (the RMS fields — auto-liquidation thresholds, buying power, etc. — populate correctly), and 358 sits in the order-plant notification range right after the 350–353 notifications. If you'd rather not commit to the mapping without an official reference, the fail-soft half (part 1) resolves the log-flood on its own and I'm happy to split this into two PRs — just let me know your preference.

Tests

Added tests/test_unknown_template.py (matches the existing plant-mock idiom):

• an unmapped template id yields a single warning, no raise, None return, and the process loop keeps dispatching subsequent messages;
• a 358 frame decodes to AccountRmsUpdates and fires on_account_rms_update.

Full suite: 30 passed locally (27 pre-existing + 3 new) via PYTHONPATH=. pytest tests on Python 3.12. No live credentials required — everything runs against the existing offline mocks.