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

@@ -1,15 +0,0 @@
-package com.correx.core.transitions.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/transitions/src/main/kotlin/com/correx/core/transitions/policy/CyclePolicyBinding.kt

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

core/transitions/src/main/kotlin/com/correx/core/transitions/policy/CyclePolicyResolver.kt

@@ -1,12 +0,0 @@
-package com.correx.core.transitions.policy
-
-class CyclePolicyResolver(
-    private val bindings: Set<CyclePolicyBinding>
-) {
-
-    fun resolve(signature: CycleSignature): CyclePolicy? {
-        return bindings
-            .firstOrNull { it.cycle == signature }
-            ?.policy
-    }
-}

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

@@ -1,9 +0,0 @@
-package com.correx.core.transitions.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/transitions/src/main/kotlin/com/correx/core/transitions/policy/CycleSignatureFactory.kt

@@ -1,19 +0,0 @@
-package com.correx.core.transitions.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/transitions/src/main/kotlin/com/correx/core/transitions/policy/PolicyValidation.kt

@@ -1,23 +0,0 @@
-package com.correx.core.transitions.policy
-
-class PolicyValidation {
-    fun validate(
-        bindings: Set<CyclePolicyBinding>,
-        knownCycles: Set<CycleSignature>
-    ): List<String> {
-
-        val errors = mutableListOf<String>()
-
-        val bound = bindings.map { it.cycle }.toSet()
-
-        val unbound = knownCycles - bound
-
-        if (unbound.isNotEmpty()) {
-            errors += unbound.map {
-                "Cycle $it has no policy binding"
-            }
-        }
-
-        return errors
-    }
-}