Feature: Contest Detail i18n & Team Management

[Sunja-An]

Description

This PR implements full internationalization for the Contest Detail page and Dashboard, adds the Team Management flow, and cleans up unused UI.

Key Changes

1. Internationalization (i18n)

• Locale Files: Updated ko.json, en.json, ja.json with comprehensive keys for:
  • contestCTA: Dynamic button states and labels.
  • contestDashboard: Tabs and action buttons.
  • contestModal: Team creation flow.
  • teamManagement: Toast messages and status.
• Components: Refactored ContestCTA, ContestDashboard, ContestApplicationModal, and page.tsx to use useTranslation.

2. Team Management Flow

• New Component: Created TeamManagementSection for inviting members ().
• Feature: Implemented client-side logic to discover the user's team ID across all games in a contest to correctly display the 'My Team' section.
• Correction: Reverted the removal of the specific Game Badge in ContestHero.

3. Cleanup & Fixes

• UI: Removed the unused "Game List" (ゲーム一覧) panel from PlaygroundMain.
• Git: Fixed .gitignore to correctly ignore docs/swagger.json.

Verification

• Verified language switching (KO/EN/JA) updates all related UI.
• Verified 'My Team' section appears correctly for joined users.
• Verified Team Invitation toast notifications.