Add version/build-date status bar to dashboard footer

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Co-authored-by: christianlouis <361235+christianlouis@users.noreply.github.com>

backend/Dockerfile

@@ -18,6 +18,10 @@ RUN pip install --no-cache-dir -r requirements.txt
 # Copy application code
 COPY . .
 
+# Inject build metadata
+ARG BUILD_DATE=""
+ENV BUILD_DATE=${BUILD_DATE}
+
 # Create non-root user
 RUN useradd -m -u 1000 appuser && \
     chown -R appuser:appuser /app