docs: add a guide for running

.env.dev

@@ -1,2 +1,5 @@
+# en-US or cs-CZ.
 LANGUAGE_CODE=en-US
+
+# Required only for mobile native client builds.
 MOBILE_SERVER_URL=

readme.md

@@ -0,0 +1,59 @@
+# Todo Baggins
+
+A task management app tailored specifically to my personal GTD workflow.
+
+## Running the web server
+
+### Development
+
+1. Copy `.env.dev` to `.env` and, if desired, edit it.
+2. Create a symlink from `docker-compose.yaml` to `docker-compose-dev.yaml`.
+3. Run the Docker compose stack with
+
+   ```sh
+   docker compose up --build -d
+   ```
+
+4. Enter the container shell with
+
+   ```sh
+   docker compose exec -it app sh
+   ```
+
+5. Inside, start the development server with
+
+   ```sh
+   dx serve --locked --addr 0.0.0.0 --port 8000
+   ```
+
+6. Once the build is finished, the web app will be accessible at
+   <http://localhost:8000>.
+
+### Production
+
+1. Copy `.env.dev` to `.env` and, if desired, edit it.
+2. Create a symlink from `docker-compose.yaml` to `docker-compose-prod.yaml`.
+3. Run the Docker compose stack with
+
+   ```sh
+   docker compose up --build -d
+   ```
+
+4. Once the build is finished, the web app will be accessible at the Docker
+   container, on port 80.
+
+## Running the Android client
+
+1. Copy `.env.dev` to `.env` and, if desired, edit it. Set the
+   `MOBILE_SERVER_URL` to the URL of the server which will be available as a
+   backend for the mobile client.
+2. Start the build with
+
+   ```sh
+   ./scripts/export_android_bundle.sh
+   ```
+
+3. Once it is finished, the APK will be present at `bundle/android`.
+4. Run the web server as described in a previous section and make it accessible
+   from the client running the mobile app at the URL specified in the
+   environment variable.