test(strix): A3 fear-modulation monotonicity + FFI NaN/Inf rejection (tests-only)

[RMANOV]

A3 bug-hunt slice — TESTS-ONLY, asserts EXISTING behavior, zero source/behavior/claim change.

• crates/strix-swarm/tests/fear_modulation.rs (NEW): integration test on the public, non-phi-sim modulate_detection_config / modulate_gossip_fanout — evade_distance strictly ↑ with fear, closing_rate_threshold strictly ↓, gossip_fanout non-decreasing & ≤ 3×base, F>1 clamps to 1, NaN/+Inf sanitize to 0.
• python/tests/test_ffi.py: NaN/Inf position rejection (ValueError) for DroneState + ParticleNavFilter via the existing validate_finite FFI boundary; mirrors the existing skip-if-not-built guard.

Gates: cargo test --workspace green; cargo clippy -p strix-swarm --all-targets -- -D warnings clean; pytest python/tests/test_ffi.py 23 passed. No src/ changes, no public docs, nothing under Project_Docs/bug_hunt/.

🤖 Generated with Claude Code

[Copilot]

Pull request overview

Adds regression tests to lock in existing fear-modulation monotonicity/sanitization behavior in strix-swarm, and to assert non-finite (NaN/Inf) position rejection at the Python FFI boundary—without changing any runtime code paths.

Changes:

• Add a new Rust integration test suite covering monotonicity, clamping, and NaN/Inf sanitization for modulate_detection_config and modulate_gossip_fanout.
• Add Python tests asserting ValueError for NaN/Inf positions for DroneState and ParticleNavFilter constructors.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
python/tests/test_ffi.py	Adds pytest coverage to ensure NaN/Inf positions are rejected at the PyO3 boundary via existing finite validation.
crates/strix-swarm/tests/fear_modulation.rs	New integration tests asserting fear-modulation monotonicity, clamping, and NaN/Inf sanitization using the public strix_swarm::fear_adapter API.

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