switch from yarn to npm

This eases build setup. Where Yarn requires a separate package
repository, npm is available in the standard one.

yarn's package repository signature was recently expired, and apparently
will expire again in a year. Avoid dealing with that.

Fixes #110.

docker/Dockerfile

@@ -30,8 +30,8 @@ FROM --platform=$BUILDPLATFORM dev-common AS build-ui
 LABEL maintainer="slamb@slamb.org"
 WORKDIR /var/lib/moonfire-nvr/src/ui
 COPY ui /var/lib/moonfire-nvr/src/ui
-RUN --mount=type=cache,target=/var/lib/moonfire-nvr/src/ui/node_modules,sharing=locked,mode=1777 \
-    yarn install && yarn build
+RUN --mount=type=tmpfs,target=/var/lib/moonfire-nvr/src/ui/node_modules \
+    npm ci && npm run build
 
 # Build the Rust components. Note that dev.sh set up an environment variable
 # in .buildrc that similarly changes the target dir path.
@@ -65,7 +65,7 @@ RUN export DEBIAN_FRONTEND=noninteractive && \
     rm -rf /var/lib/apt/lists/* && \
     ln -s moonfire-nvr /usr/local/bin/nvr
 COPY --from=build-server /usr/local/bin/moonfire-nvr /usr/local/bin/moonfire-nvr
-COPY --from=build-ui /var/lib/moonfire-nvr/ui/dist /usr/local/lib/moonfire-nvr/ui
+COPY --from=build-ui /var/lib/moonfire-nvr/src/ui/dist /usr/local/lib/moonfire-nvr/ui
 
 # The install instructions say to use --user in the docker run commandline.
 # Specify a non-root user just in case someone forgets.

docker/dev-common.bash

@@ -9,25 +9,17 @@ export DEBIAN_FRONTEND=noninteractive
 
 packages=()
 
-apt-get update
-
-# Add yarn repository.
-apt-get --assume-yes --no-install-recommends install curl gnupg ca-certificates
-curl -sS https://dl.yarnpkg.com/debian/pubkey.gpg | apt-key add -
-echo "deb https://dl.yarnpkg.com/debian/ stable main" \
-    >> /etc/apt/sources.list.d/yarn.list
-
 # Install all packages necessary for building (and some for testing/debugging).
 packages+=(
     build-essential
+    curl
     pkgconf
     locales
-    nodejs
+    npm
     sudo
     sqlite3
     tzdata
     vim-nox
-    yarn
 )
 apt-get update
 apt-get install --assume-yes --no-install-recommends "${packages[@]}"