Add Tactical Monolith design system and landing page to web app

Set up Tailwind CSS v4 with full design token system from Stitch project
(obsidian surfaces, neon cyan/magenta/lime palette, Space Grotesk + Inter
typography, 0px border-radius). Landing page includes hero section, side
nav, module cards, system status panels, terminal log, and CRT overlay.

apps/web/postcss.config.mjs

@@ -0,0 +1,8 @@
+/** @type {import('postcss-load-config').Config} */
+const config = {
+  plugins: {
+    "@tailwindcss/postcss": {},
+  },
+};
+
+export default config;