feat(usage): plan:kimi_coding 兼容 kimi-code 0.43.1 quota 用量模型

服务端 api.kimi.com/coding/v1/usages 已由绝对 used/limit 行切换为
quota 模型（usages.limit_5h/limit_7d/limit_month_total/limit_month_code，
条目为 used_ratio 0-1 比率 + reset_time），见上游 #3787。

- parse_kimi_coding 优先解析新结构，旧 limits/usage 结构保留为回退
- used_ratio >1 时按已是百分数处理（防御）
- 新 tier id month_code + 前端 planLabel/i18n 中英文案
- 新增 3 个测试：四窗口解析 / 比率防御 / 空窗口回退旧结构

src/lib/usage-display.ts

@@ -11,9 +11,10 @@ type TranslateFn = (
  *
  * Coverage note: ALL plan-type (套餐) queries flow through
  * src-tauri/src/services/coding_plan.rs::percent_tier, whose names come only
- * from TIER_FIVE_HOUR / TIER_WEEKLY_LIMIT / TIER_MONTHLY_LIMIT — so this
- * mapping covers every current and future plan provider automatically. If a
- * new tier id is ever added there, add a case here too.
+ * from TIER_FIVE_HOUR / TIER_WEEKLY_LIMIT / TIER_MONTHLY_LIMIT /
+ * TIER_MONTH_CODE — so this mapping covers every current and future plan
+ * provider automatically. If a new tier id is ever added there, add a case
+ * here too.
  */
 export function planLabel(name: string, t: TranslateFn): string {
   switch (name) {
@@ -25,6 +26,8 @@ export function planLabel(name: string, t: TranslateFn): string {
       return t("usageTierWeekly");
     case "monthly_limit":
       return t("usageTierMonthly");
+    case "month_code":
+      return t("usageTierMonthCode");
     default:
       return name;
   }