fix: add liberation fonts to Docker image and configure resvg to use them for label rendering

paperless-backend/Dockerfile

@@ -8,7 +8,7 @@ RUN npm run build
 
 # Production
 FROM node:20-alpine
-RUN apk add --no-cache ghostscript imagemagick
+RUN apk add --no-cache ghostscript imagemagick font-liberation fontconfig
 WORKDIR /app
 COPY --from=builder /app/dist ./dist
 COPY --from=builder /app/node_modules ./node_modules

paperless-backend/src/label-print-agent/label-renderer.service.ts

@@ -89,7 +89,14 @@ export class LabelRendererService {
   ${parts.join('\n  ')}
 </svg>`;
 
-    const resvg = new Resvg(svg, { font: { loadSystemFonts: true } });
+    const resvg = new Resvg(svg, {
+      font: {
+        loadSystemFonts: true,
+        fontDirs: ['/usr/share/fonts', '/usr/local/share/fonts'],
+        defaultFontFamily: 'Liberation Sans',
+        sansSerifFamily: 'Liberation Sans',
+      },
+    });
     return Buffer.from(resvg.render().asPng());
   }
 }