CODE QUALITY: Add TypeScript types and improve type safety

[jt14den]

Goal

Strengthen TypeScript usage across the codebase to catch errors early and improve developer experience.

Tasks

• Add strict TypeScript config in tsconfig.json
• Add type annotations to all React components
• Create interface for Google Sheets CSV response
• Type all props in Astro components
• Add return types to functions
• Fix any types with proper interfaces
• Run npx astro check and fix all errors
• Add JSDoc comments for complex functions
• Document type usage in STUDENT_README

Files to Focus On

• src/components/LessonFilter.jsx to .tsx
• src/components/StackedPathways.jsx to .tsx
• src/lib/getSheetData.js to .ts

Reference

See STUDENT_README.md Code Quality Tasks

[kirandharmar867-maker]

Hlo @jt14den I am intrusted to work on this issue,
i have seen Student Readme just now.
thank You.