MTR Map Overlay

Compared with v1.5.3, this release improves the Navigate API for third-party navigation mods, adds per-station availability checks, and completes four-language interface support across all six supported builds.

### Added

- **A more complete Navigate API.** Third-party navigation mods can register a provider with a per-target availability predicate and handle the selected station through the public API. The existing registration overload remains compatible; navigation integration is supplied by external mods.
- **Availability-aware navigation.** Navigate is dimmed when no registered provider can handle the selected station. Multiple available providers appear in a chooser, and availability is checked again on click.
- **Four interface languages.** English, Simplified Chinese, Traditional Chinese and Japanese cover map controls, station arrival boards, tooltips, commands and diagnostic feedback, following the game language. Player-defined station and route names remain unchanged.
- **The same features on all six platforms.** NeoForge/Fabric MC 1.21.1 builds target MTR 4.1.0-beta.2 and Java 21; Forge/Fabric MC 1.20.1 and 1.20.4 builds target MTR 4.0.5 and Java 17. Native station arrivals and full-network data require matching client and server Overlay support.

### Optimized and fixed

- Improved provider lifecycle handling: closed, stale or failing providers cannot be invoked, and one provider's failure does not disable others or repeatedly flood the log.
- Separated Xaero control text from icons and localized JourneyMap toolbar labels, PIDS style names and remaining tooltip and command messages.
- Retained native arrival boards, independent map focus and dimming, whole-map trains and pure 2D rendering. Diagnostic markers now use explicit success values instead of parsing English messages.

### 中文更新说明

相较 v1.5.3，本版完善供第三方导航模组接入的 Navigate 接口，新增逐站可用性检查，并补全四语言界面，六个平台同步提供。

**新增功能**

- **完善 Navigate 接口**：第三方导航模组可注册逐目标可用性判定，并通过公共接口处理所选车站；保留原有注册重载，具体导航适配由外部模组提供。
- **导航可用性检查**：没有可处理当前车站的已注册服务时，Navigate 按钮淡显；多个可用服务显示选择器，点击时再次验证可用性。
- **四语言界面**：英文、简体中文、繁体中文与日语覆盖地图控件、站点到站板、提示、命令与诊断反馈，跟随游戏语言。玩家自定义站名、线路名保持原样。
- **六平台功能同步**：MC 1.21.1 的 NeoForge/Fabric 包对应 MTR 4.1.0-beta.2 与 Java 21；MC 1.20.1／1.20.4 的 Forge/Fabric 包对应 MTR 4.0.5 与 Java 17。原生站点预测与全网数据需客户端和服务端安装匹配版本。

**优化与修复**

- 完善导航服务生命周期处理：关闭、过期或异常服务不会被调用，单个服务出错不会影响其它服务或反复刷日志。
- 分离 Xaero 控件文字与图标，补全 JourneyMap 工具栏、PIDS 样式名及其余提示、命令的翻译。
- 保留原生到站板、独立地图聚焦与淡化、全图列车及纯 2D 绘制；诊断标记使用明确的成功状态，不再解析英文消息。