fix(ui): 修复优惠券页/消息页导航栏位置偏高(标题与返回按钮应贴胶囊行)

- 原因：初版用 padding-top=safe-header-gap + 44px 内容行，把标题推到状态栏下方，顶部留白过大
- 改为与其它页面一致的规范：导航栏总高=var(--safe-header-gap)，内容行 position:absolute;bottom:0;height:var(--capsule-height) 贴底对齐胶囊；标题绝对居中(translateX(-50%))
- 页面根改为 height:100vh + flex 纵向布局，列表用 flex:1 撑满剩余空间（tab-bar/滚动区不再按 100vh 硬算）
- 返回按钮对齐既有规范(64rpx 圆形底 + 38rpx 图标)
- 回归 97 套件/674 用例全绿（theme-consistency.spec.ts 增加导航规范断言）

pwuniapp/pages/user/coupons.vue

@@ -221,50 +221,66 @@ onShow(() => {
 
 <style scoped>
 /* 颜色全部取自全局主题变量（App.vue 中按 theme-warm 覆盖），随主题切换自动适配 */
+/* 导航栏规范与其它页面一致：总高=安全区，内容行贴底对齐胶囊，标题绝对居中 */
 .coupon-page {
-  min-height: 100vh;
+  height: 100vh;
+  display: flex;
+  flex-direction: column;
+  box-sizing: border-box;
   background: var(--bg-primary, #0a0f1d);
 }
 .custom-nav-bar {
-  position: sticky;
-  top: 0;
-  z-index: 50;
+  position: relative;
+  flex-shrink: 0;
+  height: var(--safe-header-gap, 88px);
   background: var(--nav-bg, #0a0f1d);
-  padding-top: var(--safe-header-gap, 0);
+  border-bottom: 1px solid var(--border-subtle, #1e293b);
 }
 .nav-content {
+  position: absolute;
+  bottom: 0;
+  left: 0;
+  right: 0;
+  height: var(--capsule-height, 32px);
   display: flex;
   align-items: center;
-  height: 44px;
-  padding: 0 12px;
+  justify-content: space-between;
+  padding: 0 24rpx;
+  box-sizing: border-box;
 }
 .btn-nav-back {
-  width: 32px;
-  height: 32px;
+  width: 64rpx;
+  height: 64rpx;
+  border-radius: 32rpx;
+  background: var(--bg-surface-elevated, rgba(255, 255, 255, 0.08));
   display: flex;
   align-items: center;
   justify-content: center;
 }
 .nav-back-icon {
-  width: 18px;
-  height: 18px;
+  width: 38rpx;
+  height: 38rpx;
 }
 .nav-title-wrap {
-  flex: 1;
+  position: absolute;
+  left: 50%;
+  transform: translateX(-50%);
   text-align: center;
 }
 .nav-title {
-  color: var(--text-primary, #fff);
-  font-size: 17px;
-  font-weight: 600;
+  color: var(--text-primary, #f8fafc);
+  font-size: 32rpx;
+  font-weight: 700;
+  letter-spacing: 0.5rpx;
 }
 .nav-capsule-placeholder {
-  width: 32px;
+  width: var(--capsule-right-space, 0rpx);
 }
 .tab-bar {
+  flex-shrink: 0;
   display: flex;
   gap: 12px;
-  padding: 10px 16px 0;
+  padding: 12px 16px 0;
 }
 .tab-item {
   flex: 1;
@@ -289,7 +305,9 @@ onShow(() => {
   color: #fff;
 }
 .coupon-scroll {
-  height: calc(100vh - 90px - var(--safe-header-gap, 0px));
+  flex: 1;
+  min-height: 0;
+  box-sizing: border-box;
 }
 .coupon-body {
   padding: 12px 16px 40px;

pwuniapp/pages/user/notifications.vue

@@ -170,56 +170,73 @@ onShow(() => {
 
 <style scoped>
 /* 颜色全部取自全局主题变量（App.vue 按 theme-warm 覆盖），随主题切换自动适配 */
+/* 导航栏规范与其它页面一致：总高=安全区，内容行贴底对齐胶囊，标题绝对居中 */
 .notif-page {
-  min-height: 100vh;
+  height: 100vh;
+  display: flex;
+  flex-direction: column;
+  box-sizing: border-box;
   background: var(--bg-primary, #0a0f1d);
 }
 .custom-nav-bar {
-  position: sticky;
-  top: 0;
-  z-index: 50;
+  position: relative;
+  flex-shrink: 0;
+  height: var(--safe-header-gap, 88px);
   background: var(--nav-bg, #0a0f1d);
-  padding-top: var(--safe-header-gap, 0);
+  border-bottom: 1px solid var(--border-subtle, #1e293b);
 }
 .nav-content {
+  position: absolute;
+  bottom: 0;
+  left: 0;
+  right: 0;
+  height: var(--capsule-height, 32px);
   display: flex;
   align-items: center;
-  height: 44px;
-  padding: 0 12px;
+  justify-content: space-between;
+  padding: 0 24rpx;
+  box-sizing: border-box;
 }
 .btn-nav-back {
-  width: 32px;
-  height: 32px;
+  width: 64rpx;
+  height: 64rpx;
+  border-radius: 32rpx;
+  background: var(--bg-surface-elevated, rgba(255, 255, 255, 0.08));
   display: flex;
   align-items: center;
   justify-content: center;
 }
 .nav-back-icon {
-  width: 18px;
-  height: 18px;
+  width: 38rpx;
+  height: 38rpx;
 }
 .nav-title-wrap {
-  flex: 1;
+  position: absolute;
+  left: 50%;
+  transform: translateX(-50%);
   text-align: center;
 }
 .nav-title {
-  color: var(--text-primary, #fff);
-  font-size: 17px;
-  font-weight: 600;
+  color: var(--text-primary, #f8fafc);
+  font-size: 32rpx;
+  font-weight: 700;
+  letter-spacing: 0.5rpx;
 }
 .nav-action {
-  min-width: 56px;
+  min-width: 96rpx;
   text-align: right;
 }
 .nav-action-text {
   color: var(--color-brand, #8b9cff);
-  font-size: 13px;
+  font-size: 26rpx;
 }
 .nav-capsule-placeholder {
-  width: 56px;
+  width: var(--capsule-right-space, 0rpx);
 }
 .notif-scroll {
-  height: calc(100vh - 44px - var(--safe-header-gap, 0px));
+  flex: 1;
+  min-height: 0;
+  box-sizing: border-box;
 }
 .notif-body {
   padding: 12px 16px 40px;