refactor: reorganize type definitions and improve type safety
build: add lodash and @types/lodash as dependencies
chore: update tsconfig and vite config for path aliases
style: improve code organization and add documentation comments
fix: correct type usage in LanguageSwitcher component
perf: implement snackbar provider for global notifications
test: add new test interfaces and utility functions
ci: update pnpm-lock.yaml with new dependencies
