switch from dockerhub to ghcr, improve docker caching (#2695)

## Description:

Switch to GHCR for faster pulls/pushes and increased rate limits
Use cache-builder driver for better caching, so npm ci is cached if
dependencies don't change.



## Please complete the following:

- [x] I have added screenshots for all UI updates
- [x] I process any text displayed to the user through translateText()
and I've added it to the en.json file
- [x] I have added relevant tests to the test directory
- [x] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced

## Please put your Discord username so you can be contacted if a bug or
regression is found:

evan

Dockerfile

@@ -7,7 +7,8 @@ FROM base AS build
 ENV HUSKY=0
 # Copy package files first for better caching
 COPY package*.json ./
-RUN npm ci
+RUN --mount=type=cache,target=/root/.npm \
+    npm ci
 
 # Copy only what's needed for build
 COPY tsconfig.json ./
@@ -29,7 +30,8 @@ FROM base AS prod-deps
 ENV HUSKY=0
 ENV NPM_CONFIG_IGNORE_SCRIPTS=1
 COPY package*.json ./
-RUN npm ci --omit=dev
+RUN --mount=type=cache,target=/root/.npm \
+    npm ci --omit=dev
 
 # Final production image
 FROM base