use Arimo instead of Arial font

Signed-off-by: Kenneth Obsequio <k80308392@gmail.com>

Dockerfile

@@ -12,6 +12,10 @@ RUN npm install -g pm2 sequelize-cli
 # Not available as an apk package, so lift the binary out of pandoc/typst.
 COPY --from=typst /usr/bin/typst /usr/local/bin/typst
 
+# Arimo is metric-compatible with Arial (open license — real Arial can't be
+# bundled). certificate.typ references it by this family name.
+RUN apk add --no-cache font-arimo && fc-cache -f 2>/dev/null || true
+
 WORKDIR /app
 
 # Install production dependencies only