Serve brotli-compressed HTML with ETag support. If the client accepts br
encoding, the raw compressed bytes are sent; otherwise they are decompressed.
Returns 304 if the client’s If-None-Match matches etag.
Try to match a font route from a raw request path (any prefix).
Handles /fonts, /vt/fonts, /font/Name, /vt/font/Name%20With%20Spaces.
Returns Some(response) if the path matched a font route, None otherwise.