fix: scope company_settings query to active company in invoice dialogs (#288)

SendInvoiceDialog and PaymentBookingDialog called .single() on
company_settings without a company_id filter, relying on RLS to narrow
the result. RLS uses user_company_ids() which returns every company the
user can access, so multi-company users (including team members) got
multiple rows back and PostgREST returned 406. Filter explicitly by the
active company and use maybeSingle() so a missing row falls back to
defaults.

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

components/invoices/PaymentBookingDialog.tsx

@@ -18,6 +18,7 @@ import AccountCombobox from '@/components/bookkeeping/AccountCombobox'
 import { proposePaymentLines } from '@/lib/bookkeeping/propose-payment-lines'
 import { formatCurrency } from '@/lib/utils'
 import { createClient } from '@/lib/supabase/client'
+import { useCompany } from '@/contexts/CompanyContext'
 import { Plus, Trash2, Loader2 } from 'lucide-react'
 import type { FormLine } from '@/components/bookkeeping/JournalEntryForm'
 import type { Invoice, InvoiceItem, Customer, BASAccount, EntityType } from '@/types'
@@ -44,6 +45,7 @@ export default function PaymentBookingDialog({
 }: PaymentBookingDialogProps) {
   const { toast } = useToast()
   const supabase = createClient()
+  const { company } = useCompany()
 
   const [accounts, setAccounts] = useState<BASAccount[]>([])
   const [lines, setLines] = useState<FormLine[]>([])
@@ -68,11 +70,14 @@ export default function PaymentBookingDialog({
         const accountsData = await accountsRes.json()
         const fetchedAccounts: BASAccount[] = accountsData.data || []
 
+        if (!company?.id) throw new Error('Inget aktivt företag')
+
         // Fetch company settings
         const { data: settings, error: settingsError } = await supabase
           .from('company_settings')
           .select('accounting_method, entity_type')
-          .single()
+          .eq('company_id', company.id)
+          .maybeSingle()
 
         if (settingsError) throw new Error('Kunde inte ladda företagsinställningar')
         if (cancelled) return
@@ -116,7 +121,7 @@ export default function PaymentBookingDialog({
 
     init()
     return () => { cancelled = true }
-  }, [open, invoice.id])
+  }, [open, invoice.id, company?.id])
 
   // Balance computation
   const { totalDebit, totalCredit, isBalanced } = useMemo(() => {

components/invoices/SendInvoiceDialog.tsx

@@ -15,6 +15,7 @@ import { JournalEntryReviewContent } from '@/components/bookkeeping/JournalEntry
 import { proposeSendLines } from '@/lib/bookkeeping/propose-send-lines'
 import { formatCurrency } from '@/lib/utils'
 import { createClient } from '@/lib/supabase/client'
+import { useCompany } from '@/contexts/CompanyContext'
 import { Loader2, Mail, Send } from 'lucide-react'
 import type { Invoice, InvoiceItem, Customer, EntityType } from '@/types'
 
@@ -41,6 +42,7 @@ export default function SendInvoiceDialog({
 }: SendInvoiceDialogProps) {
   const { toast } = useToast()
   const supabase = createClient()
+  const { company } = useCompany()
 
   const [isSubmitting, setIsSubmitting] = useState(false)
   const [accountingMethod, setAccountingMethod] = useState<'accrual' | 'cash'>('accrual')
@@ -58,11 +60,14 @@ export default function SendInvoiceDialog({
 
     async function init() {
       try {
+        if (!company?.id) throw new Error('Inget aktivt företag')
+
         // Fetch company settings
         const { data: settings, error } = await supabase
           .from('company_settings')
           .select('accounting_method, entity_type')
-          .single()
+          .eq('company_id', company.id)
+          .maybeSingle()
 
         if (error) throw new Error('Kunde inte ladda företagsinställningar')
         if (cancelled) return
@@ -71,9 +76,10 @@ export default function SendInvoiceDialog({
         const { data: period } = await supabase
           .from('fiscal_periods')
           .select('name')
+          .eq('company_id', company.id)
           .lte('start_date', invoice.invoice_date)
           .gte('end_date', invoice.invoice_date)
-          .single()
+          .maybeSingle()
 
         if (cancelled) return
 
@@ -94,7 +100,7 @@ export default function SendInvoiceDialog({
 
     init()
     return () => { cancelled = true }
-  }, [open, invoice.id, invoice.invoice_date])
+  }, [open, invoice.id, invoice.invoice_date, company?.id])
 
   const proposedLines = useMemo(() => {
     if (!isInitialized || accountingMethod !== 'accrual') return []