feat: scaffold Vue 3 + Vuetify + Pinia frontend themed to FabledDesignSystem

Curator signature accent (#A87338, aged amber) is baked into
fabled-tokens.js. Vuetify theme consumes the same tokens module the rest
of the SPA does, so updating design system tokens propagates throughout.
Vite dev server proxies /api and /ws to the Quart backend.

App.vue references AppShell (lands in Task 9) and main.js references
router.js (lands in Task 9) — these are intentionally split so Task 8 is
the framework scaffold and Task 9 is the navigation/shell content.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

frontend/vite.config.js

@@ -0,0 +1,23 @@
+import { defineConfig } from 'vite'
+import vue from '@vitejs/plugin-vue'
+import vuetify from 'vite-plugin-vuetify'
+
+export default defineConfig({
+  plugins: [
+    vue(),
+    vuetify({ autoImport: true })
+  ],
+  build: {
+    outDir: 'dist',
+    emptyOutDir: true,
+    sourcemap: false
+  },
+  server: {
+    port: 5173,
+    proxy: {
+      // Dev server proxies API to local Quart
+      '/api': 'http://localhost:8080',
+      '/ws': { target: 'ws://localhost:8080', ws: true }
+    }
+  }
+})