chore: bump version to 2.21.19 in package.json and enhance invitation validation (#434)

- Updated application version from 2.21.18 to 2.21.19 in package.json.
- Improved invitation validation by handling cases where the invitation is not found and ensuring email comparison is case insensitive.

tooling/eslint/package.json

@@ -16,7 +16,7 @@
     "@next/eslint-plugin-next": "catalog:",
     "@types/eslint": "9.6.1",
     "eslint-config-next": "catalog:",
-    "eslint-config-turbo": "^2.7.0"
+    "eslint-config-turbo": "^2.7.1"
   },
   "devDependencies": {
     "@kit/prettier-config": "workspace:*",