feat: 新增部分套餐账单查询（v0.6.4）

- 账单/用量查询：balance:kimi（Moonshot 开放平台余额）、NewAPI 中转站余额（accessToken+userId）、Kimi/智谱/MiniMax 套餐档位（5小时/7天）
- managed:kimi-code 走 Kimi Code OAuth 登录凭据查询订阅用量，access token 过期自动 refresh 并写回凭据（单 flight 锁 + 写回前重读防 CLI 竞态）
- 全屏「配置用量查询」页面：启用开关 / 自动检测 vs NewAPI 模板 / 超时与自动查询间隔 / 测试查询
- 供应商卡片紧凑用量行（切换使用左侧）+ 多档明细行；managed 供应商列表置顶（仅展示层）
- 用量显示中英文适配（five_hour→5小时、weekly_limit→7天，Rust 错误串本地化映射）
- 修复：usage_kinds serde rename 导致账单入口不显示；测试查询因 save 触发 loading 翻页卸载面板导致结果丢失（silent save）

src/lib/usage-display.ts

@@ -0,0 +1,44 @@
+import type { TranslationKey } from "../i18n/zh";
+
+type TranslateFn = (
+  key: TranslationKey,
+  vars?: Record<string, string | number>
+) => string;
+
+/**
+ * Map a raw Rust plan/tier name to a localized label. Unknown names (proper
+ * nouns like "OpenRouter", "NewAPI", currency codes) pass through unchanged.
+ *
+ * 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 — 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) {
+    case "five_hour":
+      return t("usageTier5h");
+    case "weekly_limit":
+      return t("usageTierWeekly");
+    default:
+      return name;
+  }
+}
+
+/**
+ * Map known Rust error strings to localized text. Unknown errors pass
+ * through unchanged (they are diagnostic details like HTTP status + body).
+ * Keep patterns aligned with the exact prefixes emitted in
+ * src-tauri/src/commands.rs and src-tauri/src/services/*.
+ */
+export function localizeUsageError(error: string, t: TranslateFn): string {
+  if (error.startsWith("unsupported provider")) return t("usageUnsupportedProvider");
+  if (error.startsWith("no API key configured")) return t("usageErrNoKey");
+  if (error.startsWith("usage query disabled")) return t("usageErrDisabled");
+  if (/login expired|refresh failed/i.test(error)) return t("usageErrLoginExpired");
+  if (error.startsWith("no Kimi Code OAuth credentials")) return t("usageErrNoOauth");
+  if (error.startsWith("newapi template requires")) return t("usageErrNewapiCreds");
+  if (error.startsWith("Authentication failed")) return t("usageInvalidKey");
+  return error;
+}