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>

CHANGELOG.md

@@ -10,6 +10,16 @@ The first version, to be released as 0.1.0.
 
 ### Added
 
+- A logo: a Viking jarl drawn like a woodcut, with a spear-pointed crown
+  that holds a DNS tree (a root node and its branches), a stern face and a
+  full carved beard. White on a Nordic-blue disc (`assets/logo.svg`), plus an all-white
+  variant (`assets/logo-white.svg`). It is shown on the login page, links
+  home in the top left of the web UI, and is the favicon.
+- The login page shows an angular, Norse-style "JARL" wordmark drawn as
+  SVG paths (`assets/brand.js`) above a rule with a "DNS" node; it follows
+  the light and dark themes. The header's "Jarl" uses Cinzel Bold (SIL OFL),
+  self-hosted as a 13 KB Latin subset.
+
 - Web UI: wherever an address match list is entered (server, view and zone
   options such as allow-query or allow-transfer, view match lists, ACL
   elements) the existing ACLs, TSIG keys and built-in names are offered as