fix(detector): detect init-subclass input float passthrough

[prasannakotyal]

Summary

• extend INPUT_PASSTHROUGH_OUTPUT to __init_subclass__ installed fake-output entrypoints
• detect base classes that assign cls.custom_kernel = lambda d: d.float() during subclass creation
• require the submitted custom_kernel to be the subclass attribute installed by that hook

Target

KernelGuard-Red-Submission: 105

Validation

• UV_CACHE_DIR=/tmp/uvcache uv run python -m py_compile kernelguard.py
• __init_subclass__ installed custom_kernel = lambda d: d.float() sample: 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
• Dynamic type extension passed official eval on PR fix(detector): detect dynamic type input float passthrough #246 with TP 20/20, FP 20/20, surgicalness 1.0

[github-actions]

KernelGuard Blue Evaluation

• Evaluation job: 192
• Blue submission: 164
• 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/25382491170

[SinatrasC]

Thanks for the KernelGuard Flywheel Campaign contribution. This PR is now superseded by the consolidated rule-family implementation in #273, which folds this detector coverage together with the related passing-eval variants.