Remove i18n Dependency from MaplatCore

[kochizufan]

Remove i18n Logic from MaplatCore (Stateless Core)

Why

• Stateless Core: Localization (i18n) state (e.g., "current language is Japanese") belongs to the UI layer, not the Core logic.
• Flexibility: MaplatCore should pass raw data (potentially containing multiple language strings) to the UI. The UI decides how to render it based on the user's preference.
• Bundle Size: Removing i18next and related internal logic reduces bundle size and complexity.

Proposed Changes

1. Remove Dependencies & Internal Locales

• Uninstall i18next, i18next-xhr-backend, and i18next-browser-languagedetector.
• Remove src/freeze_locales.ts.

2. Remove Language State from MaplatApp

• Remove lang property from MaplatApp.
• Remove i18nLoader and handleI18n.
• Remove browserLanguage detection logic.
• Update MaplatApp constructor to NOT accept lang or translateUI options.

3. Update Data Handling (Multilingual Support)

• Concept: Core treats string-like metadata (e.g., title, label, attr) as "Opaque Data" or "Multilingual Objects". It does not try to resolve them to a specific string.
• Type Definitions:
  • Update HistMap, NowMap, and POI interfaces.
  • Change type of title, label, description, etc. from string to string | Record<string, string>.
  • Example:

    // Before
    title: string;
    
    // After
    title: string | { [lang: string]: string };

• Source Factory:
  • In src/source_ex.ts, baseDict already uses objects for titles. Ensure mapSourceFactory passes these objects through without modification.
  • Remove usages of translator (e.g. options.translator(options.url)). If dynamic URL translation is needed, it should be handled by the caller before passing options, or via a new mechanism if absolutely necessary (but likely not needed for core logic).

4. Code Refactoring details

• src/index.ts:
  • Remove i18n imports.
  • Remove translator / t function injection.
  • Remove logic that waits for i18n loading.
• src/source/mixin.ts / histmap.ts:
  • Update TypeScript interfaces to allow object types for metadata fields.
• src/functions.ts:
  • Remove data-i18n attribute replacement in createElement if it relies on internal translation (or keep it if it's just a marker for consuming app, but likely remove if it implies Core doing translation).

Migration Guide for Consumers

• MaplatUI / Custom Apps:
  • The MaplatApp instance will now expose POI and Map metadata as raw objects (e.g. { ja: "...", en: "..." }) instead of a single string.
  • Consumers must implement their own logic to select the correct language string from these objects before rendering.
  • Initialization: No need to pass lang or translator to MaplatApp.

Verification

• Build: Ensure types are correctly updated and build passes.
• Smoke Test: Verify that calling map.getMapMeta() returns the structured object for title/label instead of a string.