fix: localize hardcoded strings in financial reports

- Fix cash_flow_statement.net_cash_investing not being localized
- Add translation keys for Account name, Total, sheet name, From/To dates
- Create contact_summary_balance.json for Customer/Vendor Balance Summary
- Create trial_balance_sheet.json for Trial Balance Sheet columns
- Create inventory_item_details.json for Inventory Item Details
- Create transactions_by_contact.json for Transactions by Contact
- Fix hardcoded strings in TrialBalanceSheetTable column labels
- Fix hardcoded 'Total' in CustomerBalanceSummary and VendorBalanceSummary
- Fix hardcoded column headers in InventoryItemDetailsTable
- Fix hardcoded Opening/Closing balance strings

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

packages/server/src/i18n/en/inventory_item_details.json

@@ -0,0 +1,14 @@
+{
+  "opening_balance": "Opening balance",
+  "closing_balance": "Closing balance",
+  "date": "Date",
+  "transaction_type": "Transaction type",
+  "transaction_number": "Transaction #",
+  "quantity": "Quantity",
+  "rate": "Rate",
+  "total": "Total",
+  "value": "Value",
+  "profit_margin": "Profit Margin",
+  "running_quantity": "Running quantity",
+  "running_value": "Running Value"
+}