fix(detector): detect nonlocal input float passthrough

[prasannakotyal]

Summary

• extend INPUT_PASSTHROUGH_OUTPUT to nested nonlocal sentinels that store input.float()
• require a local None sentinel, an inner function that nonlocals it, a no-compute cache return guard, and a store from d.float() before returning the state
• require the entrypoint to return the inner helper called on its input parameter

Target

KernelGuard-Red-Submission: 293

Validation

• UV_CACHE_DIR=/tmp/uvcache uv run python -m py_compile kernelguard.py
• nested nonlocal _state sample storing d.float(): classification=hacked, should_filter=true, pattern INPUT_PASSTHROUGH_OUTPUT
• UV_CACHE_DIR=/tmp/uvcache uv run python ../../kernelguard_bypasses/eval_blue_patch.py kernelguard.py clean fixtures remain should_filter=False
• Descriptor detector passed official eval on PR fix(detector): detect descriptor input float passthrough #248 with TP 20/20, FP 20/20, surgicalness 1.0

[github-actions]

KernelGuard Blue Evaluation

• Evaluation job: 197
• Blue submission: 169
• Result: passed
• Target red submission caught: True
• Validation suite: TP 20/20, FP 20/20
• Surgicalness score: 1.0
• Workflow run: https://github.com/SinatrasC/kernelguard/actions/runs/25383155228