feat: add user locale preference to user_preferences table (#555)

* feat: add user locale preference to user_preferences table

- Introduced a new column 'locale' in the user_preferences table to store per-user UI language preferences.
- Added a CHECK constraint to ensure only supported locales ('sv', 'en') are allowed.
- Triggered a schema reload notification for the changes.

chore: declare CSS module support in TypeScript

- Added a declaration for CSS modules in globals.d.ts to enable TypeScript support for importing CSS files.

* feat: add Swish as an invoice payment method in company settings

package.json

@@ -46,6 +46,7 @@
     "lucide-react": "^0.563.0",
     "mailparser": "^3.9.8",
     "next": "16.1.5",
+    "next-intl": "^4.12.0",
     "next-themes": "^0.4.6",
     "qrcode": "^1.5.4",
     "react": "19.2.3",