feat(semaino): signal aggregation and convergence detection #85
Description
From Phase 03 PLAN.md, REQ-05 + REQ-06 + REQ-07.
Signal intelligence pipeline in semaino crate:
- Domain-agnostic signal ingestion from broadcast channel
- Per-signal-type temporal baselines (Welford's algorithm via koinon)
- Anomaly detection against baselines
- fjall state store for signal history
Convergence detection (REQ-06):
- Geo-convergence grid: detect when signals from multiple domains converge spatially
- Configurable grid resolution and time window
Alert pipeline (REQ-07):
- Deduplication of redundant alerts
- Severity classification
- Routing to appropriate notification channels
Groups REQ-05, REQ-06, REQ-07 as they form the aggregation-to-alert pipeline.