chore(frontend): 会员开通文案统一为'开通会员'

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)
Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

cfc-frontend/pages/discover/index.vue

@@ -54,7 +54,7 @@
       <view class="member-card-bg">
         <text class="member-card-icon">👑</text>
         <view class="member-card-texts">
-          <text class="member-card-title">开通家庭会员</text>
+          <text class="member-card-title">开通会员</text>
           <text class="member-card-desc">享专属折扣 · 成长服务 · 规划指导</text>
         </view>
         <view class="member-card-action">

cfc-frontend/pages/shop/cart/cart.vue

@@ -64,7 +64,7 @@
     <!-- Member Upgrade Hint -->
     <view v-if="!isMember && items.length > 0" class="member-hint" @click="goUpgrade">
       <text class="member-hint-icon">👑</text>
-      <text class="member-hint-text">开通付费会员享全场商品折扣</text>
+      <text class="member-hint-text">开通会员享全场商品折扣</text>
       <text class="member-hint-action">去开通 ›</text>
     </view>
 

cfc-frontend/pages/shop/checkout/checkout.vue

@@ -82,7 +82,7 @@
       <view v-if="!isMember" class="section member-upgrade-section" @click="goUpgrade">
         <view class="member-upgrade-row">
           <text class="member-upgrade-icon">👑</text>
-          <text class="member-upgrade-text">开通付费会员享全场商品会员专享价</text>
+          <text class="member-upgrade-text">开通会员享全场商品专享价</text>
           <text class="member-upgrade-arrow">›</text>
         </view>
       </view>

cfc-frontend/pages/shop/index/index.vue

@@ -5,7 +5,7 @@
       <view class="member-banner-content">
         <text class="member-banner-icon">👑</text>
         <view class="member-banner-texts">
-          <text class="member-banner-title">开通付费会员</text>
+          <text class="member-banner-title">开通会员</text>
           <text class="member-banner-desc">享专属折扣与成长服务</text>
         </view>
       </view>

cfc-frontend/pages/shop/payment/payment.vue

@@ -59,7 +59,7 @@
       <view v-if="showUpgradeCard" class="upgrade-card">
         <view class="upgrade-card-header">
           <text class="upgrade-card-icon">🎉</text>
-          <text class="upgrade-card-title">支付成功！开通付费会员更划算</text>
+          <text class="upgrade-card-title">支付成功！开通会员更划算</text>
         </view>
         <view class="upgrade-card-body">
           <view class="upgrade-benefit-row">