feat: add QR code generator tool

Add a sixth tool with live SVG preview, customizable foreground/background
colors, error correction level, margin control, and export as PNG (256–2048px)
or SVG. URL params enable shareable state. All processing runs client-side
via the qrcode package.

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

package.json

@@ -27,6 +27,7 @@
     "jszip": "^3.10.1",
     "lucide-react": "^0.575.0",
     "next": "^16.1.6",
+    "qrcode": "^1.5.4",
     "radix-ui": "^1.4.3",
     "react": "^19.2.4",
     "react-colorful": "^5.6.1",
@@ -40,6 +41,7 @@
     "@tailwindcss/postcss": "^4.2.0",
     "@types/figlet": "^1.7.0",
     "@types/node": "^25.3.0",
+    "@types/qrcode": "^1.5.6",
     "@types/react": "^19.2.14",
     "@types/react-dom": "^19.2.3",
     "eslint": "^9.21.0",