feat: initialize thoughts-frontend with Next.js, TypeScript, and ESLint

- Add ESLint configuration for Next.js and TypeScript support.
- Create Next.js configuration file with standalone output option.
- Initialize package.json with scripts for development, build, and linting.
- Set up PostCSS configuration for Tailwind CSS.
- Add SVG assets for UI components.
- Create TypeScript configuration for strict type checking and module resolution.

thoughts-backend/tests/app/mod.rs

@@ -0,0 +1 @@
+mod persistence;