feat(docker): add Dockerfiles and update next.config.js for admin and storefront applications

- Introduced Dockerfiles for both admin and storefront applications to streamline the build and deployment process using multi-stage builds.
- Configured the Dockerfiles to install dependencies, build the applications, and set up a minimal runtime environment.
- Updated next.config.js for both applications to enable standalone output and set the outputFileTracingRoot for proper file tracing in a monorepo setup.

This commit enhances the containerization of the applications, improving deployment efficiency and reducing image sizes.

apps/storefront/next.config.js

@@ -3,6 +3,10 @@ const path = require("path");
 
 /** @type {import('next').NextConfig} */
 const nextConfig = {
+  output: "standalone",
+  // Required in a monorepo: tells Next.js to trace files from the repo root
+  // so the standalone bundle includes files from packages/
+  outputFileTracingRoot: path.join(__dirname, "../.."),
   transpilePackages: ["@repo/convex", "@repo/types", "@repo/utils"],
   turbopack: {
     root: path.join(__dirname, "..", ".."),