feat: implement skattekonto drift detection and alerting (#525)

* feat: implement skattekonto drift detection and alerting

- Add skattekonto drift computation logic to compare Skatteverket's saldo with GL 1630 sum.
- Implement alerting mechanism for significant drift changes, with throttling to prevent alert spamming.
- Introduce database functions to sum GL 1630 entries and list unbooked skattekonto rows.

feat: create own account transfer detection

- Develop logic to detect transfers between a company's own cash accounts based on counterparty IBAN.
- Implement tests to validate detection logic under various scenarios, including matching and non-matching IBANs.

feat: establish cash accounts as a first-class entity

- Create cash_accounts table to manage routable cash accounts, replacing ad-hoc JSONB structures.
- Implement functions for listing, upserting, and managing cash accounts, including primary account designation.

feat: enhance GL line reconciliation functionality

- Modify get_unlinked_1930_lines RPC to accept any account number for reconciliation, improving flexibility for different currencies.
- Update related functions to ensure compatibility with the new cash_accounts structure.

feat: capture counterparty IBAN in transactions

- Add counterparty_iban column to transactions table to facilitate intra-account transfer detection.
- Create index for efficient lookups based on counterparty IBAN.

* feat: Enhance cash account handling and reconciliation processes

- Updated reconciliation routes to enforce cash account validation for all account numbers, including '1930'.
- Improved error handling for unknown cash accounts in reconciliation status and unmatched entries routes.
- Changed CashAccountSelector to use sessionStorage instead of localStorage for better data privacy.
- Fixed mapping for employer payroll taxes to route to the correct account (2730 instead of 2731).
- Added safety checks for company IDs in the guessCounterAccount function to prevent injection vulnerabilities.
- Introduced atomic RPC for setting primary cash accounts to avoid intermediate states during updates.
- Seeded default cash accounts for new companies to ensure reconciliation routes are accessible from day one.
- Updated email notifications for drift detection to avoid exposing sensitive financial data.
- Enhanced bank reconciliation logic to handle multi-currency transactions correctly.
- Renamed and updated tests to reflect changes in the underlying RPCs and ensure accurate coverage.
- Migrated existing cash account rules to correct mappings in compliance with Swedish accounting standards.

components/reports/BankReconciliationView.tsx

@@ -8,6 +8,7 @@ import { Badge } from '@/components/ui/badge'
 import { AccountNumber } from '@/components/ui/account-number'
 import { AlertCircle, ChevronDown, ChevronRight, Link2, Unlink, Play, Eye } from 'lucide-react'
 import { formatCurrency, formatDate } from '@/lib/utils'
+import { CashAccountSelector } from '@/components/common/CashAccountSelector'
 
 function formatAmount(amount: number): string {
   return amount.toLocaleString('sv-SE', { minimumFractionDigits: 2, maximumFractionDigits: 2 })
@@ -100,6 +101,7 @@ export function BankReconciliationView() {
 
   const [dateFrom, setDateFrom] = useState('')
   const [dateTo, setDateTo] = useState('')
+  const [accountNumber, setAccountNumber] = useState('1930')
 
   const [dryRunResults, setDryRunResults] = useState<DryRunMatch[] | null>(null)
   const [runLoading, setRunLoading] = useState(false)
@@ -117,7 +119,8 @@ export function BankReconciliationView() {
       const params = new URLSearchParams()
       if (dateFrom) params.set('date_from', dateFrom)
       if (dateTo) params.set('date_to', dateTo)
-      const qs = params.toString() ? `?${params}` : ''
+      params.set('account_number', accountNumber)
+      const qs = `?${params}`
 
       const [statusRes, glRes, unmatchedRes, matchedRes] = await Promise.all([
         fetch(`/api/reconciliation/bank/status${qs}`),
@@ -143,7 +146,7 @@ export function BankReconciliationView() {
     } finally {
       setLoading(false)
     }
-  }, [dateFrom, dateTo])
+  }, [dateFrom, dateTo, accountNumber])
 
   useEffect(() => {
     fetchAll()
@@ -159,6 +162,7 @@ export function BankReconciliationView() {
         body: JSON.stringify({
           date_from: dateFrom || undefined,
           date_to: dateTo || undefined,
+          account_number: accountNumber,
           dry_run: true,
         }),
       })
@@ -182,6 +186,7 @@ export function BankReconciliationView() {
         body: JSON.stringify({
           date_from: dateFrom || undefined,
           date_to: dateTo || undefined,
+          account_number: accountNumber,
           dry_run: false,
         }),
       })
@@ -337,6 +342,10 @@ export function BankReconciliationView() {
       <Card>
         <CardContent className="pt-6">
           <div className="flex flex-wrap items-end gap-4">
+            <CashAccountSelector
+              value={accountNumber}
+              onChange={setAccountNumber}
+            />
             <div>
               <Label>Datum från</Label>
               <input