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

lib/hooks/use-format.ts

@@ -0,0 +1,20 @@
+'use client'
+
+import { useLocale } from 'next-intl'
+import { formatDateLong as formatDateLongRaw } from '@/lib/utils'
+
+/**
+ * Client-side hook returning locale-aware formatters.
+ *
+ * Currency stays SEK with sv-SE conventions (1 234,56 kr) regardless of UI
+ * language — that's the Swedish accounting standard, not a UI string.
+ * formatDate (ISO yyyy-MM-dd) is locale-independent and exported directly
+ * from lib/utils.
+ */
+export function useFormat() {
+  const locale = useLocale()
+  return {
+    locale,
+    formatDateLong: (date: Date | string) => formatDateLongRaw(date, locale),
+  }
+}