Rewrite README in English

Turn the root README into a proper project overview: what the app
does today, the stack, how to run it locally and the current status,
instead of the short Spanish setup notes it had before. Replace the
generic SvelteKit scaffold README in frontend/ with a short one that
actually describes this client.

frontend/README.md

@@ -1,42 +1,21 @@
-# sv
+# frontend
 
-Everything you need to build a Svelte project, powered by [`sv`](https://github.com/sveltejs/cli).
+The Docker Manager web client: SvelteKit, Svelte 5 runes, TypeScript and
+Tailwind CSS v4. Talks to the Go API at `$lib/api.ts`.
 
-## Creating a project
-
-If you're seeing this, you've probably already done this step. Congrats!
+## Development
 
 ```sh
-# create a new project
-npx sv create my-app
+npm install
+npm run dev      # :5173
 ```
 
-To recreate this project with the same configuration:
-
-```sh
-# recreate this project
-npx sv@0.17.0 create --template minimal --types ts --install npm frontend
-```
-
-## Developing
-
-Once you've created a project and installed dependencies with `npm install` (or `pnpm install` or `yarn`), start a development server:
-
-```sh
-npm run dev
-
-# or start the server and open the app in a new browser tab
-npm run dev -- --open
-```
+The backend needs to be running for the container list to load, see the
+root [README](../README.md) for how to start it.
 
 ## Building
 
-To create a production version of your app:
-
 ```sh
 npm run build
+npm run preview
 ```
-
-You can preview the production build with `npm run preview`.
-
-> To deploy your app, you may need to install an [adapter](https://svelte.dev/docs/kit/adapters) for your target environment.