Feat v0.6.14 visual polish

Fix v0.6.13 spacing regressions with half-step tokens (--sp-1h 6px,
--sp-2h 10px). Purge ~65 stale hex/rgba fallback values from var() calls
including all old gold #b38a4e references. Self-host DM Sans and JetBrains
Mono woff2 fonts, eliminating Google Fonts CDN dependency. Standardize
border-radius to three tokens (--radius-sm 4px, --radius 8px, --radius-lg
12px) across all kernel CSS and 12 extension packages.

Also fixes: theme settings showing resolved mode instead of stored preference,
surface-inner overflow causing notes scrollbar and chat input clipping at
high zoom, user menu drift at scale >100% from zoom-unaware fixed positioning,
and three undefined CSS variable references.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

server/pages/templates/login.html

@@ -7,7 +7,6 @@
     <title>Armature</title>
     <link rel="icon" type="image/svg+xml" href="{{.BasePath}}/favicon.svg?v={{.Version}}">
     <link rel="icon" type="image/x-icon" href="{{.BasePath}}/favicon.ico?v={{.Version}}">
-    <link href="https://fonts.googleapis.com/css2?family=DM+Sans:opsz,wght@9..40,300;9..40,400;9..40,500;9..40,600;9..40,700&family=JetBrains+Mono:wght@400;500&display=swap" rel="stylesheet">
     <link rel="stylesheet" href="{{.BasePath}}/css/variables.css?v={{.Version}}">
     <link rel="stylesheet" href="{{.BasePath}}/css/sw-login.css?v={{.Version}}">
     <style>