Apply brand palette and typography

Reconciled two overlapping note sets — kept the intent from both,
resolved contradictions toward the more distinctive option (cream over
plain gray/white background), and fixed a couple of pairings that would
have been genuinely hard to read as written (teal button with taupe
text, rose links on taupe — both too low-contrast) by keeping the color
but swapping in white/higher-contrast text instead.

Slate blue header (firm, confident) with warm cream body (gentle,
breathing room), teal CTAs (clarity/action), dusty rose as the one purely
interactive/decorative touch (hover states), warm taupe grounding the
footer. Headings in slate blue to tie the brand color into the type
hierarchy. Roboto/Open Sans/Source Code Pro per the font pairing brief,
loaded via Google Fonts since that's what was specified.

layouts/_default/baseof.html

@@ -5,6 +5,9 @@
   <meta name="viewport" content="width=device-width, initial-scale=1">
   <title>{{ if .IsHome }}{{ .Site.Title }}{{ else }}{{ .Title }} · {{ .Site.Title }}{{ end }}</title>
   <meta name="description" content="{{ .Site.Params.description }}">
+  <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=Roboto:wght@400;700&family=Open+Sans:wght@400;600;700&family=Source+Code+Pro:wght@400;600&display=swap">
   {{ $css := resources.Get "css/main.css" }}
   {{ if hugo.IsProduction }}
     {{ $css = $css | minify | fingerprint }}