📸(frontend) inject PostHog sourcemap ID in chunks during build

Add PostHog CLI step to inject proper IDs into chunks, enabling error
tracking to map exceptions back to original source code locations
via sourcemaps.

docker/dinum-frontend/Dockerfile

@@ -11,7 +11,7 @@ RUN npm ci
 COPY .dockerignore ./.dockerignore
 COPY ./src/frontend/ .
 
-### ---- Front-end builder image ----
+# ---- Front-end builder image ----
 FROM frontend-deps AS meet-builder
 
 WORKDIR /home/frontend
@@ -21,6 +21,11 @@ ENV VITE_BUILD_SOURCEMAP="true"
 
 RUN npm run build
 
+# Inject PostHog sourcemap metadata into the built assets
+# This metadata is essential for correctly mapping errors to source maps in production
+RUN set -e && \
+    npx @posthog/cli sourcemap inject --directory ./dist/assets
+
 COPY ./docker/dinum-frontend/dinum-styles.css \
     ./dist/assets/