feat: working E2E container stack with Node-RED + InfluxDB + Grafana

- Fix Dockerfile.e2e to install EVOLV properly in Node-RED /data/
- Add measurement node E2E test flow with scaling (4-20mA to 0-5m)
- Add Grafana health check to run-e2e.sh
- Guard pumpingStation demo IIFE with require.main check
- All 10 EVOLV nodes load successfully in containerized Node-RED

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

Dockerfile.e2e

@@ -1,18 +1,29 @@
 FROM nodered/node-red:latest
 
-WORKDIR /usr/src/node-red
+# Switch to root for setup
+USER root
 
-# Copy package files and nodes source
-COPY package.json ./
-COPY nodes/ ./nodes/
+# Copy EVOLV directly into where Node-RED looks for custom nodes
+COPY package.json /data/node_modules/EVOLV/package.json
+COPY nodes/ /data/node_modules/EVOLV/nodes/
 
-# Rewrite generalFunctions dependency from git+https to local file path
-RUN sed -i 's|"generalFunctions": "git+https://[^"]*"|"generalFunctions": "file:./nodes/generalFunctions"|' package.json
+# Rewrite generalFunctions dependency to local file path (no-op if already local)
+RUN sed -i 's|"generalFunctions": "git+https://[^"]*"|"generalFunctions": "file:./nodes/generalFunctions"|' \
+    /data/node_modules/EVOLV/package.json
 
-# Install dependencies (ignore scripts to avoid postinstall git checkout)
-RUN npm install --ignore-scripts
+# Fix ownership for node-red user
+RUN chown -R node-red:root /data
+
+USER node-red
+
+# Install EVOLV's own dependencies inside the EVOLV package directory
+WORKDIR /data/node_modules/EVOLV
+RUN npm install --ignore-scripts --production
 
 # Copy test flows into Node-RED data directory
-COPY test/e2e/flows.json /data/flows.json
+COPY --chown=node-red:root test/e2e/flows.json /data/flows.json
+
+# Reset workdir to Node-RED default
+WORKDIR /usr/src/node-red
 
 EXPOSE 1880