修复拼图生成前订阅授权

新增小程序原生订阅消息授权页，在用户点击后请求生成结果通知授权。

拼图 compile_puzzle_draft 前等待授权页返回或跳过后再发起生成 action。

移除 web-view message 订阅授权路径，改用 storage/hash 回写订阅结果。

补充订阅授权测试、文档和团队踩坑记录。

miniprogram/pages/subscribe-message/index.shared.js

@@ -0,0 +1,135 @@
+/* global wx, getCurrentPages */
+
+const SUBSCRIBE_RESULT_STORAGE_KEY = 'genarrative:wechat-subscribe-result';
+
+function appendSubscribeResult(url, result) {
+  const hashIndex = String(url || '').indexOf('#');
+  const baseUrl =
+    hashIndex >= 0 ? String(url).slice(0, hashIndex) : String(url || '');
+  const rawHash = hashIndex >= 0 ? String(url).slice(hashIndex + 1) : '';
+  const nextHash = rawHash
+    .split('&')
+    .filter((part) => part && !part.startsWith('wx_subscribe_result='))
+    .concat(`wx_subscribe_result=${encodeURIComponent(result)}`)
+    .join('&');
+  return `${baseUrl}#${nextHash}`;
+}
+
+function buildSubscribeResultValue(requestId, status, reason) {
+  const segments = [requestId, status];
+  if (reason) {
+    segments.push(encodeURIComponent(reason));
+  }
+  return segments.join(':');
+}
+
+function notifyPreviousWebView(requestId, status, reason) {
+  const result = buildSubscribeResultValue(requestId, status, reason);
+  wx.setStorageSync(SUBSCRIBE_RESULT_STORAGE_KEY, result);
+  const pages = getCurrentPages();
+  const previousPage = pages.length >= 2 ? pages[pages.length - 2] : null;
+  if (previousPage && typeof previousPage.setData === 'function') {
+    previousPage.setData({
+      webViewUrl: appendSubscribeResult(previousPage.data.webViewUrl, result),
+    });
+  }
+}
+
+function resolveSubscribeStatus(result, templateId) {
+  return result && result[templateId] === 'accept'
+    ? 'success'
+    : 'skip';
+}
+
+function createSubscribeMessagePage(pageContext, options = {}) {
+  const templateId = String(options.templateId || '').trim();
+  const notifyPageResult = (methodThis, status, reason) => {
+    const page = pageContext ?? methodThis;
+    const requestId = page.requestId || '';
+    if (!requestId || page.hasNotifiedSubscribeResult) {
+      return;
+    }
+    page.hasNotifiedSubscribeResult = true;
+    notifyPreviousWebView(requestId, status, reason);
+  };
+
+  return {
+    data: {
+      title: '接收生成结果通知',
+      errorMessage: '',
+      requesting: false,
+    },
+
+    onLoad(query) {
+      const page = pageContext ?? this;
+      page.requestId = String(query.requestId || '');
+      page.hasNotifiedSubscribeResult = false;
+    },
+
+    notifyResult(status, reason) {
+      notifyPageResult(this, status, reason);
+    },
+
+    requestSubscribe() {
+      const page = pageContext ?? this;
+      const requestId = page.requestId || '';
+      if (!requestId) {
+        page.setData({
+          errorMessage: '缺少订阅请求参数。',
+        });
+        return;
+      }
+      if (!templateId) {
+        notifyPageResult(this, 'skip', 'missing_template_id');
+        wx.navigateBack();
+        return;
+      }
+      if (typeof wx.requestSubscribeMessage !== 'function') {
+        notifyPageResult(this, 'skip', 'unsupported');
+        wx.navigateBack();
+        return;
+      }
+
+      page.setData({
+        requesting: true,
+        errorMessage: '',
+      });
+      wx.requestSubscribeMessage({
+        tmplIds: [templateId],
+        success(result) {
+          notifyPageResult(
+            page,
+            resolveSubscribeStatus(result, templateId),
+            '',
+          );
+          wx.navigateBack();
+        },
+        fail(error) {
+          notifyPageResult(
+            page,
+            'skip',
+            error && error.errMsg ? error.errMsg : 'failed',
+          );
+          wx.navigateBack();
+        },
+      });
+    },
+
+    handleSkip() {
+      notifyPageResult(this, 'skip', 'user_skip');
+      wx.navigateBack();
+    },
+
+    onUnload() {
+      notifyPageResult(this, 'skip', 'page_unload');
+    },
+  };
+}
+
+module.exports = {
+  SUBSCRIBE_RESULT_STORAGE_KEY,
+  appendSubscribeResult,
+  buildSubscribeResultValue,
+  createSubscribeMessagePage,
+  resolveSubscribeStatus,
+};