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.

infrastructure/src/main/kotlin/com/correx/infrastructure/InfrastructureModule.kt

@@ -1,6 +1,7 @@
 package com.correx.infrastructure
 
 import com.correx.core.approvals.domain.ApprovalEngine
+import com.correx.core.artifactstore.ArtifactStore
 import com.correx.core.events.EventDispatcher
 import com.correx.core.events.stores.EventStore
 import com.correx.core.inference.DefaultInferenceRouter
@@ -17,6 +18,10 @@ import com.correx.infrastructure.inference.commons.ModelManager
 import com.correx.infrastructure.inference.commons.ResidencyMode
 import com.correx.infrastructure.inference.llama.cpp.DefaultModelManager
 import com.correx.infrastructure.inference.llama.cpp.LlamaCppInferenceProvider
+import com.correx.infrastructure.artifactscas.CasArtifactStore
+import kotlinx.coroutines.runBlocking
+import com.correx.infrastructure.artifactscas.config.CasConfig
+import com.correx.infrastructure.artifactscas.index.SqliteArtifactIndex
 import com.correx.infrastructure.persistence.SqliteEventStore
 import com.correx.infrastructure.tools.DefaultToolRegistry
 import com.correx.infrastructure.tools.DispatchingToolExecutor
@@ -31,17 +36,32 @@ import com.correx.infrastructure.persistence.artifact.LiveArtifactRepository
 import com.correx.core.artifacts.repository.ArtifactRepository
 import com.correx.core.artifacts.DefaultArtifactReducer
 import io.ktor.client.HttpClient
+import java.nio.file.Files
 import java.nio.file.Path
+import java.nio.file.Paths
 import java.sql.DriverManager
 
+@Suppress("TooManyFunctions")
 object InfrastructureModule {
     private val defaultDbPath: String =
         "${System.getProperty("user.home")}/.config/correx/correx.db"
 
-    fun createEventStore(dbPath: String = defaultDbPath): EventStore {
+    private val defaultArtifactsRoot: String =
+        "${System.getProperty("user.home")}/.config/correx/artifacts"
+
+    fun createEventStore(artifactStore: ArtifactStore, dbPath: String = defaultDbPath): EventStore {
         val dir = java.io.File(dbPath).parentFile
         if (!dir.exists()) dir.mkdirs()
-        return SqliteEventStore(DriverManager.getConnection("jdbc:sqlite:$dbPath"))
+        return SqliteEventStore(
+            connection = DriverManager.getConnection("jdbc:sqlite:$dbPath"),
+            artifactStore = artifactStore,
+        )
+    }
+
+    fun createArtifactStore(rootDir: Path = Paths.get(defaultArtifactsRoot)): ArtifactStore {
+        Files.createDirectories(rootDir)
+        val index = SqliteArtifactIndex(rootDir.resolve("index.sqlite"))
+        return runBlocking { CasArtifactStore.open(CasConfig(rootDir), index) }
     }
 
     fun createModelManager(