build: upgrade Tailwind CSS from v3 to v4

- Migrate from Tailwind CSS 3.x to 4.1.15
- Replace autoprefixer with @tailwindcss/postcss 4.1.15
- Update PostCSS configuration for Tailwind v4 compatibility
- Convert globals.scss to globals.css for CSS-first configuration
- Remove legacy tailwind.config.cjs in favor of CSS-based config
- Update all component imports to use new globals.css
- Remove old.tsx.disabled file

src/styles/globals.css

@@ -0,0 +1,36 @@
+@import "tailwindcss";
+@import url("https://fonts.googleapis.com/css2?family=IBM+Plex+Mono:ital,wght@0,100;0,200;0,300;0,400;0,500;0,600;0,700;1,100;1,200;1,300;1,400;1,500;1,600;1,700&family=Inter:wght@100..900&display=swap");
+
+@theme {
+  --font-sans: "Inter var", ui-sans-serif, system-ui, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol", "Noto Color Emoji";
+  --font-mono: "IBM Plex Mono", ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace;
+  --color-zinc-850: #1D1D20;
+}
+
+@source "../**/*.{js,ts,jsx,tsx}";
+
+dd {
+  margin: 0.5em 0 1em 2em;
+}
+
+.dashed {
+  border-bottom: 1px dashed silver;
+}
+
+body {
+  color-scheme: dark;
+  @apply bg-zinc-900 font-sans text-white;
+}
+
+dd,
+dl {
+  white-space: nowrap;
+}
+
+dl {
+  margin: 0;
+}
+
+.scrollbar-thin {
+  scrollbar-width: thin;
+}