fix(docker): use npm install instead of npm ci for self-contained builds

npm ci requires a package-lock.json and installs exactly what it specifies.
npm install resolves from package.json directly, making the Docker build
fully self-contained — you can clone the repo and run docker build with no
local Node tooling or pre-existing lockfile.

Dockerfile

@@ -16,7 +16,7 @@ RUN --mount=type=cache,target=/root/go/pkg/mod \
 # Copy package files and install npm dependencies (cached unless package.json changes)
 COPY package*.json ./
 RUN --mount=type=cache,target=/root/.npm \
-  npm ci
+  npm install 
 
 # Copy Go mod files (cached unless go.mod changes)
 COPY go.mod go.sum ./