fix: replace broken symlink with REPORTS_DIR env var

The ln -sf /data/reports /app/reports was creating the symlink INSIDE
/app/reports/ (since that dir already existed from COPY) instead of
replacing it. Result: sitespeed.io wrote to /app/reports/<id> and the
parser looked there too, but the volume was at /data/reports.

Fix: set REPORTS_DIR=/data/reports in Docker ENV and use it in both
runner.js (outputFolder) and app.js (static serving). No symlink needed.
Also add .dockerignore to exclude reports/, node_modules/, .git/.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Dockerfile

@@ -26,15 +26,13 @@ RUN SITESPEED_JS=$(find / -name 'sitespeed.js' -path '*/bin/*' 2>/dev/null | hea
     echo "Build-time sitespeed.js found at: $SITESPEED_JS"; \
     echo "export SITESPEED_BIN=$SITESPEED_JS" > /sitespeed_env
 
-# Create persistent directories
-RUN mkdir -p /data/reports
+# Create the persistent data directories (volume mount points)
+RUN mkdir -p /data/reports /data/db
 
-# Symlink reports dir into app folder
-RUN ln -sf /data/reports /app/reports
-
-# Runtime env
+# Runtime env — REPORTS_DIR and DB_PATH point to the mounted volumes
 ENV PORT=3132 \
     IN_DOCKER=1 \
+    REPORTS_DIR=/data/reports \
     NODE_ENV=production
 
 EXPOSE 3132