feat(m2): add contract change versioning with CHANGING state

web/delivery-platform-ui/src/api/platform.js

@@ -379,3 +379,11 @@ export function getCallbackStats(params) {
 export function getProjectHealth() {
   return axios.get('/api/v1/reports/project-health');
 }
+
+// —— I11 合同变更版本 ——————————————————————————
+export function initiateContractChange(id, body) {
+  return axios.post(`/api/v1/contracts/${id}/changes`, body);
+}
+export function completeContractChange(id) {
+  return axios.post(`/api/v1/contracts/${id}/changes/complete`);
+}

web/delivery-platform-ui/src/views/ContractDetailView.vue

@@ -132,6 +132,8 @@ import {
   listProjects,
   uploadContractAttachment,
   listContractAttachments,
+  initiateContractChange,
+  completeContractChange,
 } from "../api/platform";
 import { apiErrorMessage } from "../utils/apiErrorMessage";
 
@@ -176,6 +178,7 @@ const contractId = computed(() => route.params.id);
 
 const isDraft = computed(() => String(contract.value?.status ?? "").toUpperCase() === "DRAFT");
 const isEffective = computed(() => String(contract.value?.status ?? "").toUpperCase() === "EFFECTIVE");
+const isChanging = computed(() => String(contract.value?.status ?? "").toUpperCase() === "CHANGING");
 
 const lineRows = computed(() => {
   const c = contract.value;
@@ -475,7 +478,13 @@ function onTransition(btn) {
       if (id == null) return;
       transitionLoading.value = btn.status;
       try {
-        await patchContractStatus(id, { status: btn.status });
+        if (btn.status === "CHANGING") {
+          await initiateContractChange(id, { reason: "" });
+        } else if (btn.status === "EFFECTIVE" && isChanging.value) {
+          await completeContractChange(id);
+        } else {
+          await patchContractStatus(id, { status: btn.status });
+        }
         ElMessage.success("状态已更新");
         await refreshAll();
       } catch (e) {