Add Database page with new connection feature

- Reorganize project structure: move frontend to web/ directory
- Add Database page with connection list (name, type, subtables, status, created, actions)
- Integrate Element Plus for UI components with dark theme support
- Add Quicksand font for rounded UI design
- Configure root package.json to run frontend from web/ directory

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

web/tailwind.config.js

@@ -0,0 +1,33 @@
+/** @type {import('tailwindcss').Config} */
+export default {
+  content: [
+    "./index.html",
+    "./src/**/*.{vue,js,ts,jsx,tsx}",
+  ],
+  theme: {
+    extend: {
+      colors: {
+        dark: {
+          950: '#0a0c10',
+          900: '#0f1115',
+          800: '#121419',
+          700: '#171922',
+          600: '#1a1c25',
+          500: '#2a2c36',
+        },
+        primary: {
+          orange: '#ff9500',
+          yellow: '#ffc247',
+          cyan: '#36bffa',
+          purple: '#a78bfa',
+          danger: '#ef4444',
+          success: '#10b981',
+        }
+      },
+      fontFamily: {
+        sans: ['Quicksand', 'system-ui', 'sans-serif'],
+      },
+    },
+  },
+  plugins: [],
+}