refactor: merge cycle policy into semantic validation layer

Wire SemanticValidator into the production validator pipeline and
consolidate cycle-policy types under core:validation.

- Add SemanticValidator(CycleExitRule(requirePolicyForCycles=false))
  to the prod ValidationPipeline (no-op default, preserves behavior)
- Move CyclePolicy/Binding/Signature/Factory from core:transitions.policy
  to core:validation.policy (validation already owns ValidationContext)
- Rename CyclePolicyBindingRule -> CycleExitRule (issue code unchanged)
- Delete dead CyclePolicyResolver + PolicyValidation

core/validation/src/main/kotlin/com/correx/core/validation/model/ValidationContext.kt

@@ -3,7 +3,7 @@ package com.correx.core.validation.model
 import com.correx.core.sessions.SessionState
 import com.correx.core.transitions.analysis.DetectedCycle
 import com.correx.core.transitions.graph.WorkflowGraph
-import com.correx.core.transitions.policy.CyclePolicyBinding
+import com.correx.core.validation.policy.CyclePolicyBinding
 
 data class ValidationContext(
     val graph: WorkflowGraph,

core/validation/src/main/kotlin/com/correx/core/validation/policy/CyclePolicy.kt

@@ -0,0 +1,15 @@
+package com.correx.core.validation.policy
+
+sealed interface CyclePolicy {
+    data class Retry(
+        val maxAttempts: Int
+    ) : CyclePolicy
+
+    data class Refinement(
+        val maxIterations: Int
+    ) : CyclePolicy
+
+    data class Approval(
+        val timeoutMs: Long
+    ) : CyclePolicy
+}

core/validation/src/main/kotlin/com/correx/core/validation/policy/CyclePolicyBinding.kt

@@ -0,0 +1,6 @@
+package com.correx.core.validation.policy
+
+data class CyclePolicyBinding(
+    val cycle: CycleSignature,
+    val policy: CyclePolicy
+)

core/validation/src/main/kotlin/com/correx/core/validation/policy/CycleSignature.kt

@@ -0,0 +1,9 @@
+package com.correx.core.validation.policy
+
+import com.correx.core.events.types.StageId
+import java.util.*
+
+data class CycleSignature(
+    val nodes: SortedSet<StageId>,
+    val edges: SortedSet<Pair<StageId, StageId>>,
+)

core/validation/src/main/kotlin/com/correx/core/validation/policy/CycleSignatureFactory.kt

@@ -0,0 +1,19 @@
+package com.correx.core.validation.policy
+
+import com.correx.core.events.types.StageId
+import com.correx.core.transitions.graph.TransitionEdge
+import java.util.*
+
+object CycleSignatureFactory {
+    fun from(nodes: List<StageId>, edges: List<TransitionEdge>): CycleSignature {
+        val nodeSet = TreeSet<StageId>(compareBy { it.value })
+        nodeSet.addAll(nodes)
+
+        val edgeSet = TreeSet<Pair<StageId, StageId>>(
+            compareBy({ it.first.value }, { it.second.value })
+        )
+        edges.forEach { edgeSet.add(it.from to it.to) }
+
+        return CycleSignature(nodes = nodeSet, edges = edgeSet)
+    }
+}

core/validation/src/main/kotlin/com/correx/core/validation/semantic/rules/CycleExitRule.kt

@@ -1,12 +1,12 @@
 package com.correx.core.validation.semantic.rules
 
-import com.correx.core.transitions.policy.CycleSignatureFactory
+import com.correx.core.validation.policy.CycleSignatureFactory
 import com.correx.core.validation.model.ValidationContext
 import com.correx.core.validation.model.ValidationIssue
 import com.correx.core.validation.model.ValidationSeverity
 import com.correx.core.validation.semantic.SemanticRule
 
-class CyclePolicyBindingRule(
+class CycleExitRule(
     private val requirePolicyForCycles: Boolean
 ) : SemanticRule {