refactor(fonts): centralize Google Fonts import into index.css

[shaikayan13]

Also includes dependency fixes needed to run the dev environment locally:

• Added missing @fullcalendar/core and react-is (were causing Vite resolve errors)
• Downgraded @vitejs/plugin-react to 4.7.0 for Vite 7 compatibility
• Minor vite patch bump to 7.3.5

📋 What does this PR do?

📋 What does this PR do?

Removes duplicate Google Fonts @import statements from 19 component files (pages and FitnessChatBot). A single centralized @import in index.css was widened to cover the full weight/style range needed by all the removed duplicates, so no fonts were lost.

Also includes a few dependency fixes that were required to get the dev environment running locally:

• Added missing @fullcalendar/core and react-is (were causing Vite module resolution errors)
• Downgraded @vitejs/plugin-react to 4.7.0 for compatibility with the project's pinned Vite 7
• Minor vite patch bump to 7.3.5

🔗 Related Issue

Closes #361

🧪 How was this tested?

Ran the full app locally (npm run dev for both client and server), seeded the database, and clicked through the homepage, a product page, and the chatbot. Fonts render identically to before, with no console errors.

📸 Screenshots (if UI changes)

No visual changes — fonts render identically before and after.

✅ Checklist

• I've read the CONTRIBUTING guide
• My code follows the project's style guidelines
• I've tested my changes locally
• I've included unit tests if adding/changing core backend logic
• I've linked the related issue
• I haven't introduced any new secrets or API keys
• I've updated README.md if I added a new route, page, component, or env variable

📸 Screenshots (if UI changes)

Before / After screenshots if you changed any UI.

✅ Checklist

• I've read the CONTRIBUTING guide
• My code follows the project's style guidelines
• I've tested my changes locally
• I've linked the related issue
• I haven't introduced any new secrets or API keys