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.

testing/replay/src/test/kotlin/SessionReplayTest.kt

@@ -23,7 +23,7 @@ class SessionReplayTest {
     private val replayer = DefaultEventReplayer(store, projector)
 
     @Test
-    fun `rebuild session from event stream`() {
+    fun `rebuild session from event stream`(): Unit = kotlinx.coroutines.runBlocking {
         val sessionId = SessionId("s1")
 
         val metadataToPayload = mapOf<EventMetadata, EventPayload>(

testing/replay/src/test/kotlin/TransitionReplayIntegrationTest.kt

@@ -14,6 +14,7 @@ import com.correx.core.sessions.SessionStatus
 import com.correx.core.sessions.projections.replay.DefaultEventReplayer
 import com.correx.infrastructure.persistence.InMemoryEventStore
 import com.correx.testing.fixtures.EventFixtures.newEvent
+import kotlinx.coroutines.runBlocking
 import org.junit.jupiter.api.Assertions.assertEquals
 import org.junit.jupiter.api.Test
 
@@ -22,7 +23,7 @@ class TransitionReplayIntegrationTest {
     private val sessionId = SessionId("session-1")
 
     @Test
-    fun `workflow replay reconstructs COMPLETED session`() {
+    fun `workflow replay reconstructs COMPLETED session`(): Unit = runBlocking {
 
         val store = InMemoryEventStore()
 
@@ -85,7 +86,7 @@ class TransitionReplayIntegrationTest {
     }
 
     @Test
-    fun `workflow replay reconstructs FAILED session`() {
+    fun `workflow replay reconstructs FAILED session`(): Unit = runBlocking {
 
         val store = InMemoryEventStore()
 
@@ -144,7 +145,7 @@ class TransitionReplayIntegrationTest {
     }
 
     @Test
-    fun `replay is deterministic for identical event stream`() {
+    fun `replay is deterministic for identical event stream`(): Unit = runBlocking {
         val events = listOf(
             newEvent(
                 sessionId = sessionId,