build(docker): only copy required files

'COPY .' causes cache invalidation when any file within the repo is changed, whether they affect the build steps or not.
This means that, locally, layers constantly have to be rebuilt. Instead, this copies the files required at that step.

Refs #390

Dockerfile

@@ -16,12 +16,15 @@ COPY ./package* ./
 
 RUN npm ci
 
-COPY . .
-
-ENV NODE_ENV=production
-
-# Avoid lscpu warning on Alpine
-#ENV PARCEL_WORKERS=1
+COPY \
+  .parcelrc \
+  .prettierignore \
+  .prettierrc \
+  .sassrc \
+  .terserrc \
+  tsconfig.json \
+  ./
+COPY src/ src/
 
 RUN npm run build
 
@@ -33,6 +36,12 @@ RUN npm run build
 FROM build AS dev
 ENV NODE_ENV=development
 
+COPY \
+  .gitignore \
+  .proxyrc \
+  docker-entrypoint.sh \
+  ./
+
 ENTRYPOINT ["./docker-entrypoint.sh"]
 CMD ["start:dev"]