Register TACO rebound notification plugin

[Pigbibi]

Summary

• add taco_rebound_shadow to the shared strategy plugin registry for tqqq_growth_income only
• document notification-only semantics and supported alert channels
• cover compatibility checks and alert behavior without a trade flag

Tests

• PYTHONPATH=src pytest tests/test_strategy_plugins.py -q
• PYTHONPATH=src ruff check src/quant_platform_kit/common/strategy_plugins.py src/quant_platform_kit/common/init.py tests/test_strategy_plugins.py