[NDH-301] add i18next dependency, address frontend dependency confusion

Author: abachman-dsac

backend/docker-compose.yml

@@ -65,7 +65,8 @@ services:
       - '8000:8000'
     volumes:
       - '.:/app'
-      - ./artifacts:/app/artifacts
+      - ./artifacts:/app/artifacts:rw
+      - ./provider_directory/static:/app/provider_directory/static:rw
     depends_on:
       - db
 

frontend/.dockerignore

@@ -0,0 +1,2 @@
+**/node_modules
+

frontend/README.md

@@ -34,11 +34,35 @@ From the `npd` project root:
 
 1. Ensure that a suitable docker service is running
 1. Run `docker compose up --build` to launch the backend and frontend applications
+   - If you want to run the application backend and frontend separately, you can do that with:
+     ```console
+     ~/npd $ docker compose up -d django-web
+     ~/npd $ docker compose up -d web
+     ```
+1. Happy coding!
 
-- If you want to run the application backend and frontend separately, you can do that with:
-  ```console
-  ~/npd $ docker compose up -d django-web
-  ~/npd $ docker compose up -d web
-  ```
+### Adding Dependencies
 
-1. Happy coding!
+Because of our current frontend docker compose setup, new dependencies **MUST** be installed with `docker compose run web npm install`. They will not be picked up by `docker compose build web` or `docker compose up --build web`.
+
+The reason is that we are mounting a virtual docker compose volume in place of the container's `/app/node_modules` directory, but `docker compose build` doesn't know about _runtime_ volume mounts, only _host_ and _base image_ mounts, so it cannot update the docker compose virtual volume, only the directory which is present inside the image during the build process.
+
+For us, this means that if you are running in docker containers with `docker compose` and want to add a frontend dependency, you'll need to make sure they are added inside the running container with `docker compose run npm install`, as well as outside (on your host machine) if you need that for editor support or to run `npm` commands on host.
+
+```sh
+# install and save a new dependency on host, to make the editor tooling happy
+cd frontend
+npm install --save i18next
+
+# in docker, to make the image happy
+docker compose run --rm web npm install
+```
+
+Likewise, if `package.json` has been updated since you last fetched project updates, you'll need to run:
+
+```sh
+# after `git pull` when frontend/package.json has been updated
+docker compse run --rm web npm install
+```
+
+to refresh your local frontend docker compose `web` service.

frontend/package-lock.json

@@ -18,6 +18,7 @@
     "@cmsgov/design-system": "^13.0.0",
     "@uswds/uswds": "3.13.0",
     "classnames": "^2.5.1",
+    "i18next": "^25.6.0",
     "react": "^19.1.1",
     "react-dom": "^19.1.1",
     "react-router": "^7.9.4"