BUG: 定价解析器为价格相同的模型返回聚合路由(主测试失败)

tests/test_pricing.py::test_resolves_common_bare_model_names fails on current main (v1.6.2, 52b1923):

    assert resolve_litellm_model("grok-4.5") == "xai/grok-4.5"
E   AssertionError: assert 'openrouter/x-ai/grok-4.5' == 'xai/grok-4.5'

Full run: 1740 passed, 1 failed.

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