Web UI: Jarl logo and wordmark

Add the logo, a Viking jarl drawn like a woodcut whose spear-pointed crown
holds a DNS tree. It is generated by scripts/logo.py, which mirrors the
left half so the figure is exactly symmetrical, as logo.svg (white on a
Nordic-blue disc) and logo-white.svg. It links home in the header, sits on
the login page and is the favicon.

The login page shows an angular "JARL" wordmark drawn as SVG paths over a
rule with a "DNS" node, coloured from the theme. The header's "Jarl" uses
a self-hosted Cinzel Bold subset (SIL OFL); jarld serves .woff2 as
font/woff2.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/web/web.go

@@ -5,8 +5,14 @@ package web
 import (
 	"embed"
 	"io/fs"
+	"mime"
 )
 
+func init() {
+	// Not in Go's built-in table, and the server sends nosniff.
+	mime.AddExtensionType(".woff2", "font/woff2")
+}
+
 //go:embed static
 var static embed.FS