Prioritize case-local BFCL equivalent tools

[SonAIengine]

Summary

• Detect when retrieved BFCL candidates contain a case-local tool surface and equivalent sibling tools.
• Move the case-local equivalent surface to the front of the model-facing candidate list while preserving the original retrieved list for search evidence.
• Add an explicit description hint for the preferred equivalent function name.
• Document the near-duplicate disambiguation result and update the next bottleneck notes.

Validation

• poetry run ruff check .
• poetry run ruff format --check .
• poetry run pytest tests/test_bfcl_tool_selection_llm_loop.py tests/test_bfcl_tool_selection_sweep.py -q -> 29 passed
• poetry run pytest tests/ -q -> 965 passed, 3 skipped, 1 warning
• Fresh Qwen 27B near-duplicate 4-case subset: evaluator exact 1.0, retrieval@5 1.0, failure tags {}
• Fresh Qwen 27B argument 6-case subset regression check: evaluator exact 1.0, retrieval@5 1.0, failure tags {}

Qwen smoke artifacts

• /tmp/gtc-bfcl-neardup-case-local-order.json
• /tmp/gtc-bfcl-neardup-order-argument-subset.json

Notes

• This is stacked on Preserve BFCL argument values in model schemas #53 because Tag BFCL argument mismatch causes #51/Prefer case-local BFCL tool schemas #52/Preserve BFCL argument values in model schemas #53 are still open on GitHub.

[SonAIengine]

Closing this internal stacked PR as superseded by the current main branch. The branch is preserved for history.