feat: add layout shell — BaseLayout, SiteNav, SiteFooter [2/3] (#10141)

## Summary
Adds the layout shell for the marketing site: SEO head, analytics, nav,
and footer.

## Changes (incremental from #10140)
- BaseLayout.astro: SEO meta (OG/Twitter), GTM (GTM-NP9JM6K7), Vercel
Analytics, ClientRouter, i18n
- SiteNav.vue: Fixed nav with logo, Enterprise/Gallery/About/Careers
links, COMFY CLOUD + COMFY HUB CTAs, mobile hamburger with ARIA
- SiteFooter.vue: Product/Resources/Company/Legal columns, social icons

## Stack (via Graphite)
- #10140 [1/3] Scaffold ← merge first
- **[2/3] Layout Shell** ← this PR
- #10142 [3/3] Homepage Sections

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-10141-feat-add-layout-shell-BaseLayout-SiteNav-SiteFooter-2-3-3266d73d365081aeb2d7e598943a8e17)
by [Unito](https://www.unito.io)

packages/design-system/src/css/style.css

@@ -1,6 +1,7 @@
 @layer theme, base, primevue, components, utilities;
 
 @import './fonts.css';
+@import './_palette.css';
 @import 'tailwindcss/theme' layer(theme);
 @import 'tailwindcss/utilities' layer(utilities);
 @import 'tw-animate-css';
@@ -31,38 +32,10 @@
   --text-3xs: 0.5625rem;
   --text-3xs--line-height: calc(1 / 0.5625);
 
-  /* Font Families */
-  --font-inter: 'Inter', sans-serif;
-
-  /* Palette Colors */
-  --color-charcoal-100: #55565e;
-  --color-charcoal-200: #494a50;
-  --color-charcoal-300: #3c3d42;
-  --color-charcoal-400: #313235;
-  --color-charcoal-500: #2d2e32;
-  --color-charcoal-600: #262729;
-  --color-charcoal-700: #202121;
-  --color-charcoal-800: #171718;
-
-  --color-neutral-550: #636363;
-
-  --color-ash-300: #bbbbbb;
-  --color-ash-500: #828282;
-  --color-ash-800: #444444;
-
   --color-ivory-100: #fdfbfa;
   --color-ivory-200: #faf9f5;
   --color-ivory-300: #f0eee6;
 
-  --color-smoke-100: #f3f3f3;
-  --color-smoke-200: #e9e9e9;
-  --color-smoke-300: #e1e1e1;
-  --color-smoke-400: #d9d9d9;
-  --color-smoke-500: #c5c5c5;
-  --color-smoke-600: #b4b4b4;
-  --color-smoke-700: #a0a0a0;
-  --color-smoke-800: #8a8a8a;
-
   --color-sand-100: #e1ded5;
   --color-sand-200: #fff7d5;
   --color-sand-300: #888682;
@@ -72,14 +45,6 @@
   --color-slate-200: #9fa2bd;
   --color-slate-300: #5b5e7d;
 
-  --color-white: #ffffff;
-  --color-black: #000000;
-
-  --color-electric-400: #f0ff41;
-  --color-sapphire-700: #172dd7;
-  --color-brand-yellow: var(--color-electric-400);
-  --color-brand-blue: var(--color-sapphire-700);
-
   --color-azure-300: #78bae9;
   --color-azure-400: #31b9f4;
   --color-azure-600: #0b8ce9;