重构(会员契约): 充值中心会员状态改用强类型 token

- ProfileMembershipResponse.status 由裸 String 改为 ProfileMembershipStatusToken，与前端 ProfileMembershipStatus 对齐
- BFF 直接用 From<RuntimeProfileMembershipStatus> 转换，测试改用具名枚举

server-rs/crates/api-server/src/runtime_profile.rs

@@ -1914,7 +1914,7 @@ fn build_profile_recharge_center_response(
     ProfileRechargeCenterResponse {
         mud_point_balance,
         membership: ProfileMembershipResponse {
-            status: record.membership.status.as_str().to_string(),
+            status: record.membership.status.into(),
             plan: record.membership.plan.into(),
             started_at: record.membership.started_at,
             expires_at: record.membership.expires_at,

server-rs/crates/shared-contracts/src/runtime.rs

@@ -433,7 +433,8 @@ pub struct ProfileMembershipPlanResponse {
 #[derive(Clone, Debug, Serialize, Deserialize, PartialEq)]
 #[serde(rename_all = "camelCase")]
 pub struct ProfileMembershipResponse {
-    pub status: String,
+    /// 会员状态 token：`normal` / `active`。
+    pub status: ProfileMembershipStatusToken,
     /// 当前档位 token；非会员与已到期都是 `normal`。
     pub plan: ProfileMembershipPlanToken,
     pub started_at: Option<String>,
@@ -1819,7 +1820,7 @@ mod tests {
                 permanent_points: 4,
             },
             membership: ProfileMembershipResponse {
-                status: "active".to_string(),
+                status: ProfileMembershipStatusToken::Active,
                 plan: ProfileMembershipPlanToken::Plus,
                 started_at: Some("2026-04-25T10:00:00Z".to_string()),
                 expires_at: Some("2026-05-25T10:00:00Z".to_string()),
@@ -1929,7 +1930,7 @@ mod tests {
         let center = ProfileRechargeCenterResponse {
             mud_point_balance: empty_mud_point_balance(),
             membership: ProfileMembershipResponse {
-                status: "normal".to_string(),
+                status: ProfileMembershipStatusToken::Normal,
                 plan: ProfileMembershipPlanToken::Normal,
                 started_at: None,
                 expires_at: None,
@@ -2005,7 +2006,7 @@ mod tests {
         let center = ProfileRechargeCenterResponse {
             mud_point_balance: empty_mud_point_balance(),
             membership: ProfileMembershipResponse {
-                status: "normal".to_string(),
+                status: ProfileMembershipStatusToken::Normal,
                 plan: ProfileMembershipPlanToken::Normal,
                 started_at: None,
                 expires_at: None,