Hannya mark and Shippori Mincho B1 wordmark

Replace the Kamon ghost with the horned Hannya mask in favicon.svg,
apple-touch-icon.png, the web UI and the setup page. The wordmark and
katakana use Shippori Mincho B1 ExtraBold, bundled as a subset (ASCII
and katakana, 21 KB) under the SIL OFL and served from the binary.

web.go

@@ -8,7 +8,7 @@ import (
 // The web UI and its icons are built into the binary. The UI talks only to
 // /api/v1, the same API the iOS app uses.
 //
-//go:embed index.html setup.html app.js setup.js app.css favicon.svg apple-touch-icon.png
+//go:embed index.html setup.html app.js setup.js app.css favicon.svg apple-touch-icon.png ShipporiMinchoB1-ExtraBold.woff2
 var webFiles embed.FS
 
 func webHandler() http.Handler {
@@ -18,6 +18,9 @@ func webHandler() http.Handler {
 		case "/", "/app.js", "/setup.js", "/app.css", "/favicon.svg", "/apple-touch-icon.png":
 			w.Header().Set("Cache-Control", "no-cache")
 			files.ServeHTTP(w, r)
+		case "/ShipporiMinchoB1-ExtraBold.woff2":
+			w.Header().Set("Cache-Control", "public, max-age=31536000, immutable")
+			files.ServeHTTP(w, r)
 		case "/favicon.ico":
 			// Browsers ask for this by default; point them to the SVG.
 			http.Redirect(w, r, "/favicon.svg", http.StatusMovedPermanently)