docs: resolve OQ-03 — adopt rolling token window screening (ADR-012)

Research confirmed rolling token windows as the right approach for long
document screening. ADR-012 formalizes the decision: Phase 2 implements
screen_document() with 25% overlap (512 tokens for SmolLM2-135M), max
pooling aggregation, and character offset tracking. Short inputs fall
through to screen() unchanged.

This resolves the last open question. All 6 original OQs are now resolved:
- OQ-01: ONNX removed (burn/cublas better future path)
- OQ-02: 65% codebook compression achievable
- OQ-03: Rolling token windows for Phase 2 (ADR-012)
- OQ-04: Both model-specific defaults + user-overridable
- OQ-05: Standalone API + thin adapters (ADR-011)
- OQ-06: TOML for file-based config

docs/architecture/overview.md

@@ -185,6 +185,7 @@ All design decisions are documented as ADRs in [decisions/](decisions/).
 | [009](decisions/009-last-token-extraction.md) | Last-token activation extraction | Standard for autoregressive models; full sequence context |
 | [010](decisions/010-monotonic-spline-distributions.md) | Monotonic spline distributions | Compact, smooth, tail-sensitive behavioral region modeling |
 | [011](decisions/011-guardrail-integration-strategy.md) | Standalone API + thin adapters | Phase 1 standalone, Phase 2 thin adapter packages |
+| [012](decisions/012-rolling-window-screening.md) | Rolling token window screening | Phase 2 `screen_document()` with 25% overlap, max pooling |
 
 ## Dependencies on Other Projects