Internationalization: Add Multi-language Support

## Description

Add multi-language support (i18n) to the FairMind platform to make it accessible to users worldwide.

## Why This Is a Good First Issue

- High impact feature
- Can be implemented incrementally
- Good learning opportunity for i18n
- Clear scope and requirements
- Well-documented patterns available

## Current State

- Application is English-only
- No internationalization infrastructure
- Text is hardcoded in components

## Goals

1. **Set Up i18n Infrastructure**
- Choose i18n library (next-intl, react-i18next, etc.)
- Configure translation system
- Set up language detection

2. **Extract Text**
- Identify all user-facing text
- Extract to translation files
- Organize by feature/page

3. **Implement Language Switching**
- Language selector component
- Persist language preference
- Update UI dynamically

4. **Initial Languages**
- English (default)
- Spanish
- French
- Additional languages as needed

## Getting Started

1. **Prerequisites**
- React/Next.js knowledge
- Understanding of i18n concepts
- Familiarity with translation workflows

2. **Recommended Library**
- `next-intl` (recommended for Next.js)
- Or `react-i18next` with `next-i18next`

3. **Files to Modify**
- `apps/frontend-new/src/app/` - Page files
- `apps/frontend-new/src/components/` - Component files
- Create `messages/` directory for translations

4. **Implementation Steps**
- Install i18n library
- Configure Next.js for i18n
- Extract text to translation files
- Add language switcher component
- Test language switching
- Add additional languages

## Acceptance Criteria

- [ ] i18n infrastructure set up
- [ ] All user-facing text extracted
- [ ] Language switcher implemented
- [ ] At least 2 languages supported
- [ ] Language preference persisted
- [ ] Documentation updated

## Resources

- [next-intl Documentation](https://next-intl-docs.vercel.app/)
- [React i18next](https://react.i18next.com/)
- [i18n Best Practices](https://www.i18next.com/principles/best-practices)

## Related

Related to parent issue #133 (Platform Enhancements & User Experience)

## Labels
enhancement, help wanted, good first issue, frontend