Skip font inlining in whiteboard SVG export

exportToSvg's font-embedding path (base64 @font-face rules) goes through
the browser FontFace API, which jsdom doesn't implement -- that's what
crashed fontFacesStylesGenerator after the previous global-shimming fix
got past startup. skipInliningFonts avoids that path entirely; resvg
already falls back to system fonts for rasterizing regardless, so
embedded fonts were never going to affect the final PNG.

server/render-service/server.js

@@ -96,6 +96,13 @@ app.post('/render', async (req, res) => {
       appState: appState || {},
       files: files || {},
       exportPadding: 20,
+      // Font embedding (base64 @font-face rules in the SVG's <defs>) goes
+      // through the browser's FontFace API, which jsdom doesn't implement
+      // and can't be meaningfully polyfilled here -- and we don't need
+      // it anyway: resvg (below) already falls back to whatever fonts
+      // fontconfig finds (see ../Dockerfile's fonts-dejavu-core), so
+      // embedded fonts were never going to make it into the final PNG.
+      skipInliningFonts: true,
     });
     // Depending on the installed version, exportToSvg resolves to either
     // an SVGSVGElement (needs serializing) or already a string -- handle