fix(detector): detect function defaults replay

[prasannakotyal]

KernelGuard-Red-Submission: 183

Detects replay through mutable storage installed into custom_kernel.__defaults__ and loaded inside the entrypoint.

The pass requires:

• module-level mutation of custom_kernel.__defaults__ with mutable storage
• local alias loaded from that defaults tuple
• a no-compute fast path whose test does not depend on live input
• fast-path return by subscript from the alias
• mutation of that same alias inside the entrypoint

Local validation:

• uv run python -m py_compile kernelguard.py
• uv run python /home/nino/repos/paradigma/kernelguard_bypasses/eval_blue_patch.py /home/nino/repos/paradigma/competition_state/kernelguard_mirror/kernelguard.py

Target red fixture: red_67_function_defaults_replay.py

[github-actions]

KernelGuard Blue Evaluation

• Evaluation job: 139
• Blue submission: 111
• 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/25254314821

[SinatrasC]

Thanks for the KernelGuard Flywheel Campaign contribution. We are not merging this narrow variant separately because the consolidated rule-family implementation in #273 is the merge path for this detector area.