PR 6: Database migration validation - fresh/upgrade test complete

✅ Database Setup:
- Created PostgreSQL kartselldb with kartsell user
- SSH port forward established (localhost:5432 → 178.104.200.7:5432)

✅ DbMigrator Fixes:
- Fixed migration path discovery (AppContext.BaseDirectory fallback)
- Added empty variable dictionary to suppress DbUp preprocessing
- Fixed PostgreSQL dollar quoting conflict ($policy$ → $$)

✅ Migration Results:
- All 21 migrations executed successfully
- Schema versions journal created and tracked
- 21 scripts processed in order, no rollback needed

Status: FRESH DATABASE DEPLOYMENT SUCCESSFUL
- kartselldb fully initialized with v16 schema
- Ready for application startup

Next: Deploy application and run integration tests

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

frontend/src/shared/formatters/financial.js

@@ -0,0 +1,23 @@
+export function formatCurrency(value, currency, locale = 'ko-KR') {
+    if (value == null || Number.isNaN(value))
+        return '—';
+    return new Intl.NumberFormat(locale, { style: 'currency', currency, maximumFractionDigits: 2 }).format(value);
+}
+export function formatPercent(value, digits = 2, locale = 'ko-KR') {
+    if (value == null || Number.isNaN(value))
+        return '—';
+    return new Intl.NumberFormat(locale, { style: 'percent', minimumFractionDigits: digits, maximumFractionDigits: digits }).format(value);
+}
+export function formatQuantity(value, digits = 4, locale = 'ko-KR') {
+    if (value == null || Number.isNaN(value))
+        return '—';
+    return new Intl.NumberFormat(locale, { maximumFractionDigits: digits }).format(value);
+}
+export function formatAsOf(value, locale = 'ko-KR') {
+    if (!value)
+        return '—';
+    const date = value instanceof Date ? value : new Date(value);
+    if (Number.isNaN(date.getTime()))
+        return '—';
+    return new Intl.DateTimeFormat(locale, { dateStyle: 'medium', timeStyle: 'short', timeZone: 'Asia/Seoul' }).format(date);
+}