feat(cas): content-addressed artifact store (steps 1–8)

New core:artifacts-store interface + infrastructure/artifacts-cas
implementation: segment files + SQLite index, Blake3 hashing,
group-commit fsync via flushBefore, recovery tail-scan, manual
compactor, and oldest-first disk-cap evictor.

Inference events now carry promptArtifactId / responseArtifactId;
orchestrators put bytes before emitting. SqliteEventStore wraps
its txn in artifactStore.flushBefore so segment data is fsynced
before the event commit, making the crash window non-corrupting
(TailScanner re-indexes orphan tail records on reopen).

Compactor and evictor are mutually exclusive via maintenanceMutex.
Step 9 (cloud sync) deferred to a later epic.

See docs/reviews/2026-05-18-cas-steps-1-8-review.md for the final
review.

core/events/src/main/kotlin/com/correx/core/events/EventDispatcher.kt

@@ -12,7 +12,7 @@ import kotlinx.datetime.Clock
 import java.util.*
 
 class EventDispatcher(private val eventStore: EventStore) {
-    fun emit(
+    suspend fun emit(
         payload: EventPayload,
         sessionId: SessionId,
         causationId: CausationId? = null,

core/events/src/main/kotlin/com/correx/core/events/events/InferenceEvents.kt

@@ -1,5 +1,6 @@
 package com.correx.core.events.events
 
+import com.correx.core.events.types.ArtifactId
 import com.correx.core.events.types.InferenceRequestId
 import com.correx.core.events.types.ProviderId
 import com.correx.core.events.types.SessionId
@@ -14,6 +15,7 @@ data class InferenceStartedEvent(
     val sessionId: SessionId,
     val stageId: StageId,
     val providerId: ProviderId,
+    val promptArtifactId: ArtifactId,
 ) : EventPayload
 
 @Serializable
@@ -24,6 +26,7 @@ data class InferenceCompletedEvent(
     val providerId: ProviderId,
     val tokensUsed: TokenUsage,
     val latencyMs: Long,
+    val responseArtifactId: ArtifactId,
 ) : EventPayload
 
 @Serializable

core/events/src/main/kotlin/com/correx/core/events/stores/EventStore.kt

@@ -14,12 +14,12 @@ interface EventStore {
      * - idempotency by eventId
      * - causal consistency rules (if enforced here, otherwise in kernel)
      */
-    fun append(event: NewEvent): StoredEvent
+    suspend fun append(event: NewEvent): StoredEvent
 
     /**
      * Append multiple events atomically (same session preferred).
      */
-    fun appendAll(events: List<NewEvent>): List<StoredEvent>
+    suspend fun appendAll(events: List<NewEvent>): List<StoredEvent>
 
     /**
      * Read events for a session in strict sequence order.
@@ -41,4 +41,10 @@ interface EventStore {
      * Does not replay historical events — use [readFrom] for catch-up before subscribing.
      */
     fun subscribe(sessionId: SessionId): Flow<StoredEvent>
+
+    /**
+     * Iterate every event in the store across all sessions, in monotonic insertion order.
+     * Intended for batch jobs (e.g. CAS liveness scans). Implementations should stream lazily.
+     */
+    fun allEvents(): Sequence<StoredEvent>
 }