Add built-in localization support for multiple languages

[derrickmehaffy]

Feature Description

Add comprehensive localization (i18n) support to HyperFactions with translations bundled directly in the mod JAR. All player-facing text should be translatable, allowing servers to run in any supported language.

Proposed Solution

Bundled language files inside JAR:

resources/
  lang/
    en_US.json    # English (default)
    es_ES.json    # Spanish
    de_DE.json    # German
    fr_FR.json    # French
    pt_BR.json    # Portuguese (Brazil)
    zh_CN.json    # Chinese (Simplified)
    ja_JP.json    # Japanese
    ru_RU.json    # Russian
    ko_KR.json    # Korean
    pl_PL.json    # Polish
    it_IT.json    # Italian
    nl_NL.json    # Dutch
    tl-PH.json    # Philippines

Configuration:

language: en_US          # Server-wide default language
per_player_locale: true  # Use player's client locale when available
fallback_locale: en_US   # Fallback if translation missing

Translation coverage - ALL player-facing text:

Category	Examples
Commands	Success/error messages, confirmations, usage hints
GUI Labels	Button text, headers, descriptions, tooltips
GUI Help Pages	All help content, tutorials, explanations
Chat Messages	Faction announcements, alerts, notifications
Territory Messages	Enter/leave messages, claim feedback
Error Messages	Permission denied, invalid input, cooldowns
Relation Messages	Alliance requests, war declarations, truces
Power Messages	Power gain/loss notifications
Admin Messages	Admin command feedback, warnings

Excluded from localization:

• Console debug logs (remain in English for developer debugging)
• Log file entries
• Internal error stack traces

Translation key format:

{
  "command.create.success": "Faction {faction} has been created!",
  "command.create.error.name_taken": "A faction with that name already exists.",
  "gui.home.title": "Faction Home",
  "gui.home.button.members": "Members",
  "gui.help.claiming.title": "How to Claim Territory",
  "gui.help.claiming.description": "Stand in a chunk and use /f claim to claim it for your faction.",
  "territory.enter.faction": "~ {faction} ({relation}) ~",
  "territory.enter.safezone": "~ SafeZone ~",
  "power.gained": "You gained {amount} power. ({current}/{max})",
  "error.no_permission": "You don't have permission to do that.",
  "error.not_in_faction": "You must be in a faction to use this command."
}

Placeholder support in translations:

• {player} - Player name
• {faction} - Faction name
• {amount} - Numeric values
• {current} / {max} - Current/max values
• {relation} - Relation type (Ally, Enemy, etc.)
• {time} - Formatted time values

Implementation approach:

1. Create LocalizationManager class to load and cache translations
2. Use message keys throughout codebase instead of hardcoded strings
3. Provide Lang.get(key, placeholders...) utility method
4. Auto-detect player locale from client settings (if per_player_locale enabled)
5. Graceful fallback chain: Player locale → Server default → en_US → Raw key

Alternatives Considered

1. External lang files in config folder - User requested against this; harder to distribute translations
2. Resource pack based - Client-side only, doesn't work for chat messages
3. Database-stored translations - Overcomplicated for this use case
4. Crowdin/Weblate integration - Could be added later for community translations

Additional Context

• Translations bundled in JAR ensure all servers get updates automatically
• Community can contribute translations via GitHub PRs
• Consider adding /f admin lang reload for hot-reloading during testing
• GUI help pages are extensive - significant translation effort needed
• Permission messages should use consistent terminology across languages
• RTL (right-to-left) language support may require additional GUI work