feat: initial brainstorming app — Nuxt 3 + SQLite + admin auth

Nuxt 3 app with:
- SQLite (better-sqlite3) for persistence
- Anonymous idea submission and voting
- Admin auth with session cookies
- AI analysis via Gemini API
- Nuxt UI components + Tailwind

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

nuxt.config.ts

@@ -0,0 +1,14 @@
+export default defineNuxtConfig({
+  compatibilityDate: '2025-01-01',
+  future: { compatibilityVersion: 4 },
+  modules: ['@nuxt/ui'],
+
+  runtimeConfig: {
+    adminPassword: process.env.ADMIN_PASSWORD || 'admin',
+    dbPath: process.env.DB_PATH || './data/brainstorm.db',
+  },
+
+  nitro: {
+    experimental: { tasks: true },
+  },
+})