Add classifier hits and alerts pipeline

Add NATS subjects + ClickHouse tables for classifier hits/alerts, evaluate sweep/spike rules in compute, expose API/WS endpoints, and cover storage helpers with tests.

packages/storage/src/classifier-hits.ts

@@ -0,0 +1,70 @@
+import type { ClassifierHitEvent } from "@islandflow/types";
+
+export const CLASSIFIER_HITS_TABLE = "classifier_hits";
+
+export type ClassifierHitRecord = {
+  source_ts: number;
+  ingest_ts: number;
+  seq: number;
+  trace_id: string;
+  classifier_id: string;
+  confidence: number;
+  direction: string;
+  explanations_json: string;
+};
+
+export const classifierHitsTableDDL = (): string => {
+  return `
+CREATE TABLE IF NOT EXISTS ${CLASSIFIER_HITS_TABLE} (
+  source_ts UInt64,
+  ingest_ts UInt64,
+  seq UInt64,
+  trace_id String,
+  classifier_id String,
+  confidence Float64,
+  direction String,
+  explanations_json String
+)
+ENGINE = MergeTree
+ORDER BY (source_ts, seq)
+`;
+};
+
+export const toClassifierHitRecord = (hit: ClassifierHitEvent): ClassifierHitRecord => {
+  return {
+    source_ts: hit.source_ts,
+    ingest_ts: hit.ingest_ts,
+    seq: hit.seq,
+    trace_id: hit.trace_id,
+    classifier_id: hit.classifier_id,
+    confidence: hit.confidence,
+    direction: hit.direction,
+    explanations_json: JSON.stringify(hit.explanations)
+  };
+};
+
+const safeJsonArray = (value: string): string[] => {
+  try {
+    const parsed = JSON.parse(value);
+    if (Array.isArray(parsed)) {
+      return parsed.map((entry) => String(entry));
+    }
+  } catch {
+    // ignore
+  }
+
+  return [];
+};
+
+export const fromClassifierHitRecord = (record: ClassifierHitRecord): ClassifierHitEvent => {
+  return {
+    source_ts: record.source_ts,
+    ingest_ts: record.ingest_ts,
+    seq: record.seq,
+    trace_id: record.trace_id,
+    classifier_id: record.classifier_id,
+    confidence: record.confidence,
+    direction: record.direction,
+    explanations: safeJsonArray(record.explanations_json)
+  };
+};