feat: scaffold Antonym fashion store

Anonymous Bitcoin-only fashion e-commerce with:
- Vue 3 + Tailwind 4 frontend with glassmorphism dark/light design system
- Express 5 + SQLite backend with BTCPay Server integration
- Nostr identity (NIP-07/keypair) for anonymous purchase tracking
- ChaCha20-Poly1305 encrypted shipping addresses
- Admin panel with order/product/stock management
- SVG logo splash animation with clip-path reveal
- 5 seeded products across 4 categories

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

server/db/connection.ts

@@ -0,0 +1,22 @@
+import Database from 'better-sqlite3'
+import path from 'node:path'
+import fs from 'node:fs'
+import { fileURLToPath } from 'node:url'
+
+const __dirname = path.dirname(fileURLToPath(import.meta.url))
+const DB_PATH = path.join(__dirname, '..', '..', 'data', 'antonym.db')
+
+let db: Database.Database | null = null
+
+export function getDb(): Database.Database {
+  if (!db) {
+    const dir = path.dirname(DB_PATH)
+    if (!fs.existsSync(dir)) {
+      fs.mkdirSync(dir, { recursive: true })
+    }
+    db = new Database(DB_PATH)
+    db.pragma('journal_mode = WAL')
+    db.pragma('foreign_keys = ON')
+  }
+  return db
+}