fix(docker): drop host package-lock.json before npm install in build

Lock files generated on Windows/macOS pin platform-specific Rollup native
binaries (e.g. @rollup/rollup-win32-x64-msvc) and won't bring in the Linux
ones the Docker image needs. Symptom: `MODULE_NOT_FOUND` on
`rollup/dist/native.js` during `npm run build:docker`. See npm/cli#4828.

Removing the lock inside the build forces a fresh, Linux-native dep
resolution. Side effect: a tiny loss of cross-build version pinning, which
is acceptable here — `npm install` honours the version ranges in
package.json so semver-compatible patches at most slip in.

The proper long-term fix is to regenerate package-lock.json on Linux and
commit that. Until then this rm guards every Docker build.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Dockerfile.standalone

@@ -76,7 +76,14 @@ WORKDIR /app
 COPY frontend/ frontend/
 COPY scripts/ scripts/
 WORKDIR /app/frontend
-RUN npm install && npm run build:docker
+# Drop any host-generated package-lock.json before installing. A lock
+# generated on Windows/macOS pins platform-specific Rollup/esbuild binaries
+# (e.g. @rollup/rollup-win32-x64-msvc) and won't install the Linux variants
+# this image needs — manifests as MODULE_NOT_FOUND in rollup/dist/native.js
+# during the build. See npm/cli#4828.
+RUN rm -f package-lock.json \
+ && npm install --include=optional \
+ && npm run build:docker
 
 
 # ---- Stage 2: Final Production Image ----