[codex] rename tech pullback cash buffer profile

[Pigbibi]

What changed

• renamed the IBKR-facing canonical strategy profile from cash_buffer_branch_default to tech_pullback_cash_buffer
• updated runtime config resolution, platform registry, env examples, workflow checks, README, and tests to use the new canonical name
• renamed the canonical config and daily overlay research assets to the new strategy name
• removed legacy alias support and added explicit tests that the old profile name is rejected

Why

The old profile name was an engineering label and hard to understand from the outside. tech_pullback_cash_buffer is clear enough to tell what the strategy is doing, and we can do a clean one-shot migration because this line is still paper-only.

Validation

• python3 -m py_compile runtime_config_support.py strategy_registry.py research/backtest_growth_pullback_v1_4_cash_buffer_refinement.py research/backtest_growth_pullback_v1_5_freeze_review.py research/backtest_tech_pullback_cash_buffer_daily_overlay.py tests/test_runtime_config_support.py tests/test_strategy_loader.py tests/test_snapshot_strategy_runtime.py tests/test_feature_snapshot_service.py tests/test_execution_service.py tests/test_rebalance_service.py tests/test_growth_pullback_v1_4_cash_buffer_refinement.py tests/test_growth_pullback_v1_5_freeze_review.py tests/test_tech_pullback_cash_buffer_daily_overlay.py
• python3 -m ruff check runtime_config_support.py strategy_registry.py research/backtest_growth_pullback_v1_4_cash_buffer_refinement.py research/backtest_growth_pullback_v1_5_freeze_review.py research/backtest_tech_pullback_cash_buffer_daily_overlay.py tests/test_runtime_config_support.py tests/test_strategy_loader.py tests/test_snapshot_strategy_runtime.py tests/test_feature_snapshot_service.py tests/test_execution_service.py tests/test_rebalance_service.py tests/test_growth_pullback_v1_4_cash_buffer_refinement.py tests/test_growth_pullback_v1_5_freeze_review.py tests/test_tech_pullback_cash_buffer_daily_overlay.py
• PYTHONPATH=/Users/lisiyi/Projects/InteractiveBrokersPlatform:/Users/lisiyi/Projects/UsEquityStrategies:/Users/lisiyi/Projects/UsEquityStrategies/src:/Users/lisiyi/Projects/CryptoStrategies:/Users/lisiyi/Projects/CryptoStrategies/src:/Users/lisiyi/Projects/QuantPlatformKit/src /Users/lisiyi/Projects/InteractiveBrokersPlatform/.venv/bin/python -m pytest tests/test_runtime_config_support.py tests/test_strategy_loader.py tests/test_snapshot_strategy_runtime.py tests/test_feature_snapshot_service.py tests/test_execution_service.py tests/test_rebalance_service.py tests/test_tech_pullback_cash_buffer_daily_overlay.py tests/test_growth_pullback_v1_4_cash_buffer_refinement.py tests/test_growth_pullback_v1_5_freeze_review.py
• bash tests/test_sync_cloud_run_env_workflow.sh