add Tailwind and design tokens to frontend.

Tailwind v4 via Vite plugin, theme tokens in main.css, and VS Code hints for v4 at-rules.

frontend/src/App.vue

@@ -1,32 +1,6 @@
 <template>
-    <main class="home">
-        <h1>Private Image</h1>
+    <main class="flex min-h-screen flex-col p-8">
+        <h1 class="text-2xl font-semibold tracking-tight">Private Image</h1>
+        <p class="mt-2 text-muted-foreground">Privacy-first image hosting — upload UI coming soon.</p>
     </main>
 </template>
-
-<style scoped>
-.home {
-    box-sizing: border-box;
-    min-height: 100vh;
-    margin: 0;
-    padding: 2rem;
-    font-family:
-        system-ui,
-        -apple-system,
-        Segoe UI,
-        Roboto,
-        sans-serif;
-    line-height: 1.5;
-}
-
-h1 {
-    margin: 0 0 0.5rem;
-    font-size: 1.75rem;
-    font-weight: 600;
-}
-
-p {
-    margin: 0;
-    color: #444;
-}
-</style>

frontend/src/assets/css/main.css

@@ -0,0 +1,75 @@
+@import 'tailwindcss';
+
+@custom-variant dark (&:is(.dark *));
+
+@theme inline {
+    --radius-sm: calc(var(--radius) - 4px);
+    --radius-md: calc(var(--radius) - 2px);
+    --radius-lg: var(--radius);
+    --radius-xl: calc(var(--radius) + 4px);
+    --color-background: var(--background);
+    --color-foreground: var(--foreground);
+    --color-card: var(--card);
+    --color-card-foreground: var(--card-foreground);
+    --color-primary: var(--primary);
+    --color-primary-foreground: var(--primary-foreground);
+    --color-secondary: var(--secondary);
+    --color-secondary-foreground: var(--secondary-foreground);
+    --color-muted: var(--muted);
+    --color-muted-foreground: var(--muted-foreground);
+    --color-accent: var(--accent);
+    --color-accent-foreground: var(--accent-foreground);
+    --color-destructive: var(--destructive);
+    --color-border: var(--border);
+    --color-input: var(--input);
+    --color-ring: var(--ring);
+}
+
+:root {
+    --radius: 0.5rem;
+    --background: oklch(0.99 0.002 260);
+    --foreground: oklch(0.2 0.02 260);
+    --card: oklch(1 0 0);
+    --card-foreground: oklch(0.2 0.02 260);
+    --primary: oklch(0.42 0.08 260);
+    --primary-foreground: oklch(0.99 0.002 260);
+    --secondary: oklch(0.96 0.01 260);
+    --secondary-foreground: oklch(0.28 0.03 260);
+    --muted: oklch(0.96 0.008 260);
+    --muted-foreground: oklch(0.48 0.02 260);
+    --accent: oklch(0.94 0.02 260);
+    --accent-foreground: oklch(0.28 0.03 260);
+    --destructive: oklch(0.55 0.2 25);
+    --border: oklch(0.9 0.01 260);
+    --input: oklch(0.9 0.01 260);
+    --ring: oklch(0.42 0.08 260);
+}
+
+.dark {
+    --background: oklch(0.16 0.02 260);
+    --foreground: oklch(0.96 0.01 260);
+    --card: oklch(0.2 0.02 260);
+    --card-foreground: oklch(0.96 0.01 260);
+    --primary: oklch(0.72 0.1 260);
+    --primary-foreground: oklch(0.18 0.02 260);
+    --secondary: oklch(0.24 0.02 260);
+    --secondary-foreground: oklch(0.96 0.01 260);
+    --muted: oklch(0.24 0.02 260);
+    --muted-foreground: oklch(0.68 0.02 260);
+    --accent: oklch(0.28 0.03 260);
+    --accent-foreground: oklch(0.96 0.01 260);
+    --destructive: oklch(0.62 0.2 25);
+    --border: oklch(0.32 0.02 260);
+    --input: oklch(0.32 0.02 260);
+    --ring: oklch(0.72 0.1 260);
+}
+
+@layer base {
+    * {
+        @apply border-border;
+    }
+
+    body {
+        @apply bg-background text-foreground antialiased;
+    }
+}

frontend/src/main.ts

@@ -1,4 +1,5 @@
 import { createApp } from 'vue';
+import '@/assets/css/main.css';
 import App from './App.vue';
 
 createApp(App).mount('#app');