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/supabase/middleware.ts

@@ -1,6 +1,7 @@
 import { createServerClient } from '@supabase/ssr'
 import { NextResponse, type NextRequest } from 'next/server'
 import { shouldEnforceMfa } from '@/lib/auth/mfa'
+import { DEFAULT_LOCALE, LOCALE_COOKIE, isLocale } from '@/i18n/config'
 import { userHasPassword } from '@/lib/auth/has-password'
 
 export async function updateSession(request: NextRequest) {
@@ -135,7 +136,7 @@ export async function updateSession(request: NextRequest) {
 
     // MFA required but user has no factor enrolled yet → force enrollment
     // Skip for users with no companies (still setting up)
-    const companyIdForMfa = await resolveCompanyForMiddleware(supabase, user.id, request)
+    const { companyId: companyIdForMfa } = await resolveCompanyForMiddleware(supabase, user.id, request)
     if (companyIdForMfa) {
       const { data: factors } = await supabase.auth.mfa.listFactors()
       const hasVerifiedFactor = factors?.totp?.some(f => f.status === 'verified')
@@ -152,7 +153,7 @@ export async function updateSession(request: NextRequest) {
 
   // Company context resolution
   const cookieCompanyId = request.cookies.get('gnubok-company-id')?.value
-  const companyId = await resolveCompanyForMiddleware(supabase, user.id, request)
+  const { companyId, locale: dbLocale } = await resolveCompanyForMiddleware(supabase, user.id, request)
 
   // If the cookie pointed at a company we can no longer resolve (e.g.
   // archived), clear it so the browser stops sending it.
@@ -160,6 +161,20 @@ export async function updateSession(request: NextRequest) {
     supabaseResponse.cookies.set('gnubok-company-id', '', { path: '/', maxAge: 0 })
   }
 
+  // Sync the locale cookie from user_preferences. This keeps next-intl's
+  // request config (which reads the cookie) consistent with the DB value
+  // without forcing every RSC render to query the database itself.
+  const cookieLocale = request.cookies.get(LOCALE_COOKIE)?.value
+  const effectiveLocale = isLocale(dbLocale) ? dbLocale : DEFAULT_LOCALE
+  if (cookieLocale !== effectiveLocale) {
+    supabaseResponse.cookies.set(LOCALE_COOKIE, effectiveLocale, {
+      path: '/',
+      sameSite: 'lax',
+      secure: process.env.NODE_ENV === 'production',
+      maxAge: 60 * 60 * 24 * 365,
+    })
+  }
+
   // Routes that stay accessible when the user has no active company.
   // Needed so a user who archived their last company can still delete
   // their account without being trapped on /onboarding forever.
@@ -230,14 +245,16 @@ async function resolveCompanyForMiddleware(
   supabase: ReturnType<typeof createServerClient>,
   userId: string,
   _request: NextRequest
-): Promise<string | null> {
+): Promise<{ companyId: string | null; locale: string | null }> {
   // 1. user_preferences (authoritative)
   const { data: prefs } = await supabase
     .from('user_preferences')
-    .select('active_company_id')
+    .select('active_company_id, locale')
     .eq('user_id', userId)
     .maybeSingle()
 
+  const locale = (prefs?.locale as string | undefined) ?? null
+
   if (prefs?.active_company_id) {
     const { data: membership } = await supabase
       .from('company_members')
@@ -247,7 +264,7 @@ async function resolveCompanyForMiddleware(
       .is('companies.archived_at', null)
       .maybeSingle()
 
-    if (membership) return membership.company_id
+    if (membership) return { companyId: membership.company_id, locale }
   }
 
   // 2. Fallback: first non-archived membership by created_at
@@ -260,7 +277,7 @@ async function resolveCompanyForMiddleware(
     .limit(1)
     .maybeSingle()
 
-  if (!firstCompany) return null
+  if (!firstCompany) return { companyId: null, locale }
 
   // Write the fallback back to user_preferences so future RLS lookups
   // see the same active company without needing this fallback scan.
@@ -271,5 +288,5 @@ async function resolveCompanyForMiddleware(
       { onConflict: 'user_id' }
     )
 
-  return firstCompany.company_id
+  return { companyId: firstCompany.company_id, locale }
 }