feat(library): event_volatility macro-event strategy corpus

[AetherAI3]

PR A - Nano event corpus (Red-Folder Event Strategy Program)

Adds nano/library/event_volatility/ - 11 source/IR pairs for deterministic red-folder release trading, per the Aether Red-Folder Event Strategy Program.

Strategies

Slug	Kind
event_impulse_pullback_long / _short	Reaction-only continuation (no release values needed)
cpi_impulse_pullback_long / _short	Release-aware twin-armed trap; requires RELEASE_CONFIRMED and mutually exclusive CPI_COOL_SCORE / CPI_HOT_SCORE
event_false_first_move_long / _short	Failed pre-event-range break, anchor reclaim/reject reversal
event_second_leg_long / _short	Impulse, compression, fresh-extreme continuation
event_liquidity_halt / event_release_integrity_halt / event_whipsaw_halt	PAUSE-only controls; never execution candidates

Guarantees

• Every entry stays inside the baseline v0.1.0 subset (one every, one if, AND-chained nonnegative literals); all IR compiled via compile_to_dict(), byte-stable nanoIrVersion: 0.1.0.
• Signed release surprise is expressed as separate bull/bear series so twin arms cannot both qualify.
• New docs: docs/event_signal_contract.md (full host signal contract) + library README macro-event signal table.
• Tests: category added to EXPECTED_CATEGORIES; new execution tests cover twin-arm mutual exclusivity, ENTRY_WINDOW_OPEN gating, and the integrity halt.

Evidence

py -m pytest -q -> 375 passed, 2 skipped.

Known limitations

• Thresholds are versioned initial values from the program doc; calibration lands after golden-event fixtures replay in ATSv2 (companion PR there).
• Gamma-wall and divergence-fade strategies deferred (observe-only until provider-backed Greeks exist).

Rollback: revert this commit; the category is additive and nothing on the host side imports it until the ATSv2 event plane lands.

🤖 Generated with Claude Code