feat: Add Income Statement to DashboardPage + fix account types

- Add Income Statement section with Revenue and Expenses tables
- Color-code revenue (green) and expenses (red)
- Show Net Income prominently at bottom
- Fix SQL query to use LOWER() for case-insensitive matching
- Update account types in DB (asset/liability/revenue/expense/equity)
- Balance Sheet and Income Statement now work correctly

backend/ledger/robust_client.go

@@ -147,7 +147,7 @@ func (c *RobustClient) GetIncomeStatement(ctx context.Context, period string) (*
 		FROM boc_chart_of_accounts a
 		LEFT JOIN boc_journal_lines jl ON a.id = jl.account_id
 		LEFT JOIN boc_journal_entries je ON jl.entry_id = je.id AND je.entry_date >= $1::date AND je.entry_date < ($1::date + INTERVAL '1 month')
-		WHERE a.account_type IN ('Revenue', 'Expense')
+		WHERE LOWER(a.account_type) IN ('revenue', 'expense')
 		GROUP BY a.id, a.account_code, a.name, a.account_type
 		ORDER BY a.account_code
 	`, period+"-01")