feat(onboarding): add finish step with confetti

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

package.json

@@ -61,6 +61,7 @@
     "argon2": "^0.43.1",
     "bcrypt": "^6.0.0",
     "better-auth": "1.6.11",
+    "canvas-confetti": "^1.9.4",
     "class-variance-authority": "^0.7.1",
     "clsx": "^2.1.1",
     "cmdk": "^1.1.1",
@@ -116,6 +117,7 @@
     "@release-it/bumper": "^7.0.5",
     "@release-it/conventional-changelog": "^10.0.6",
     "@tailwindcss/postcss": "^4.3.0",
+    "@types/canvas-confetti": "^1.9.0",
     "@types/eslint-plugin-tailwindcss": "^3.17.0",
     "@types/node": "^22.19.19",
     "@types/node-forge": "^1.3.14",