feat(workflow): typed produces slots — StageConfig uses TypedArtifactSlot, TOML accepts {name, kind} objects

core/transitions/src/main/kotlin/com/correx/core/transitions/graph/StageConfig.kt

@@ -1,11 +1,10 @@
 package com.correx.core.transitions.graph
 
+import com.correx.core.artifacts.kind.TypedArtifactSlot
 import com.correx.core.events.types.ArtifactId
 import com.correx.core.inference.GenerationConfig
 import com.correx.core.inference.ModelCapability
-import kotlinx.serialization.Serializable
 
-@Serializable
 data class StageConfig(
     val requiredCapabilities: Set<ModelCapability> = emptySet(),
     val tokenBudget: Int = 4096,
@@ -16,7 +15,7 @@ data class StageConfig(
     ),
     val allowedTools: Set<String> = emptySet(),
     val maxRetries: Int = 3,
-    val produces: Set<ArtifactId> = emptySet(),
+    val produces: List<TypedArtifactSlot> = emptyList(),
     val needs: Set<ArtifactId> = emptySet(),
     val metadata: Map<String, String> = emptyMap(),
 )