Add favicon: mountain/horizon/sun mark

SVG mark plus PNG fallbacks (32x32, apple-touch-icon), wired into
the page head. Reuses the site's existing accent/ink colors.

layouts/_default/baseof.html

@@ -6,6 +6,9 @@
   <title>{{ if .IsHome }}{{ .Site.Title }}{{ else }}{{ .Title }} · {{ .Site.Title }}{{ end }}</title>
   <meta name="description" content="{{ .Site.Params.description }}">
   <link rel="alternate" type="application/rss+xml" title="{{ .Site.Title }}" href="{{ "index.xml" | absURL }}">
+  <link rel="icon" type="image/svg+xml" href="{{ "favicon.svg" | absURL }}">
+  <link rel="icon" type="image/png" sizes="32x32" href="{{ "favicon-32.png" | absURL }}">
+  <link rel="apple-touch-icon" sizes="180x180" href="{{ "apple-touch-icon.png" | absURL }}">
   <link rel="preconnect" href="https://fonts.googleapis.com">
   <link rel="preconnect" href="https://fonts.gstatic.com" crossorigin>
   <link rel="stylesheet" href="https://fonts.googleapis.com/css2?family=Fraunces:opsz,wght@9..144,400;9..144,600&family=Work+Sans:wght@400;500;600&display=swap">

static/favicon.svg

@@ -0,0 +1,6 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 32 32">
+  <circle cx="17" cy="16" r="5.5" fill="#d9531e"/>
+  <polygon points="4,26 14,10 22,26" fill="#241f19"/>
+  <polygon points="12,26 22,13 30,26" fill="#241f19"/>
+  <rect x="0" y="25" width="32" height="2" fill="#241f19"/>
+</svg>