Refactor database interactions and update footer text

- Removed community sharing and self-hosted features from the features list in page.tsx.
- Updated footer text in layout.tsx to remove the MIT License mention.
- Added @libsql/client dependency to package.json and bun.lock for database management.
- Implemented a new db.ts file to handle SQLite database connections and migrations.
- Refactored user and file management functions in users.ts and store.ts to utilize the new database client.
- Ensured legacy JSON data is imported into the new SQLite database structure on first run.

frontend/next.config.ts

@@ -14,6 +14,7 @@ const securityHeaders = [
 
 const nextConfig: NextConfig = {
   output: "standalone",
+  serverExternalPackages: ["@libsql/client"],
   experimental: {
     serverActions: {
       bodySizeLimit: "500mb",