feat(frontend): multi-language support (i18n) & real-time funding progress bar

[teethaking]

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Summary

This PR addresses two frontend improvements for NovaFund's global audience and engagement experience — full i18n support for English, Spanish, and French, and a live-updating funding progress bar powered by WebSockets and framer-motion.

Closes #307, Closes #302

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#307 — Multi-Language Support (i18n)

What changed

• Set up react-i18next and configured the provider in frontend/src/app/layout.tsx
• Extracted all hardcoded English strings from the landing page and dashboard into locale files under public/locales/:

  public/locales/en/translation.json
  public/locales/es/translation.json
  public/locales/fr/translation.json
  

• Replaced all hardcoded strings across landing and dashboard views with t() calls — 100% string coverage
• Added a language selector component in the footer allowing users to switch between English, Spanish, and French; selection is persisted to localStorage

How to verify

• Open the app and use the footer language selector to switch to Spanish or French
• Assert all visible text on the landing page and dashboard updates without a page reload
• Assert the selected language persists across page refreshes

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#302 — Real-time Funding Progress Bar

What changed

• Integrated a WebSocket connection to the backend investment event stream inside frontend/src/components/ProjectCard.tsx
• Progress bar width now updates instantly whenever a new investment event is received over the socket — no page reload required
• Animated the progress bar transition using framer-motion for a smooth interpolation between old and new percentages
• WebSocket connection cleans up on component unmount to prevent memory leaks

How to verify

• Open a project card and trigger an investment event from the backend
• Assert the progress bar advances in real-time without a reload
• Assert the animation transitions smoothly between the previous and updated percentage values
• Assert no WebSocket connection warnings appear in the console after navigating away from the page

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Checklist

• react-i18next configured in layout.tsx
• 100% string coverage on landing and dashboard
• All three locale files populated (en, es, fr)
• Language selector visible in footer, persists on reload
• WebSocket connection established and cleaned up correctly
• Progress bar animates smoothly via framer-motion
• No hardcoded English strings remaining in covered pages
• Closes Add Multi-Language Support (i18n) #307, Closes Implement Real-time Funding Progress Bar #302

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[teethaking]

awaiting merge