feat: add Resend integration for email verification and update package dependencies

- Integrated Resend for sending email verification upon user sign-up.
- Updated package.json to include Resend as a dependency.
- Enhanced authentication flow with error handling for email sending.
- Removed outdated Canvas Implementation Guide documentation.

package.json

@@ -24,6 +24,7 @@
     "radix-ui": "^1.4.3",
     "react": "19.2.4",
     "react-dom": "19.2.4",
+    "resend": "^4.8.0",
     "shadcn": "^4.1.0",
     "sonner": "^2.0.7",
     "tailwind-merge": "^3.5.0",