ops: cache NAS build dependencies

Install npm dependencies and the amd64 Rust target before copying changing source files so routine builds can reuse those layers.

Co-Authored-By: Codex <noreply@anthropic.com>

Dockerfile.nas

@@ -9,11 +9,13 @@ RUN printf '#!/bin/sh\nexit 1\n' > /usr/local/bin/git \
     && chmod +x /usr/local/bin/git
 
 WORKDIR /src
+COPY package.json package-lock.json ./
+RUN npm ci
+
 COPY . .
 
 ARG GITHUB_SHA=unknown
-RUN npm ci \
-    && npm run build
+RUN npm run build
 
 FROM --platform=$BUILDPLATFORM rust:bookworm AS server-builder
 
@@ -29,13 +31,13 @@ RUN sed -i \
         gcc-x86-64-linux-gnu libc6-dev-amd64-cross \
     && rm -rf /var/lib/apt/lists/*
 
+RUN rustup target add x86_64-unknown-linux-gnu
+
 WORKDIR /src
 COPY . .
 COPY --from=client-builder /src/client_bundle /src/client_bundle
 COPY --from=client-builder /src/version.json /src/version.json
 
-RUN rustup target add x86_64-unknown-linux-gnu
-
 ENV CARGO_TARGET_X86_64_UNKNOWN_LINUX_GNU_LINKER=x86_64-linux-gnu-gcc \
     CC_x86_64_unknown_linux_gnu=x86_64-linux-gnu-gcc