feat: integrate Grafana dashboards into BOC DashboardPage

- Add Infrastructure Health section with CPU/Memory/Disk panels
- Add Service Status section with PM2/Docker panels
- Create GrafanaPanel component for iframe embedding
- Build passes successfully

backend/service/finance.go

@@ -0,0 +1,83 @@
+package service
+
+import (
+	"context"
+	"database/sql"
+	"fmt"
+
+	"boc/repository"
+)
+
+// FinanceService handles business logic for finance operations
+type FinanceService struct {
+	repo *repository.FinanceRepository
+	db   *sql.DB
+}
+
+func NewFinanceService(db *sql.DB) *FinanceService {
+	return &FinanceService{
+		repo: repository.NewFinanceRepository(db),
+		db:   db,
+	}
+}
+
+// ListInvoices returns all invoices
+func (s *FinanceService) ListInvoices(ctx context.Context) ([]repository.Invoice, error) {
+	return s.repo.ListInvoices(ctx)
+}
+
+// ListExpenses returns all expenses
+func (s *FinanceService) ListExpenses(ctx context.Context) ([]repository.Expense, error) {
+	return s.repo.ListExpenses(ctx)
+}
+
+// CreateExpense creates a new expense with validation
+func (s *FinanceService) CreateExpense(ctx context.Context, e *repository.Expense) error {
+	if e.Category == "" {
+		return fmt.Errorf("expense category is required")
+	}
+	if e.Amount <= 0 {
+		return fmt.Errorf("expense amount must be positive")
+	}
+	if e.Status == "" {
+		e.Status = "pending"
+	}
+	return s.repo.CreateExpense(ctx, e)
+}
+
+// GetCashFlow returns income, outstanding, and expenses
+func (s *FinanceService) GetCashFlow(ctx context.Context) (income, outstanding, expenses float64, err error) {
+	return s.repo.GetCashFlow(ctx)
+}
+
+// GetAccounts returns all ledger accounts
+func (s *FinanceService) GetAccounts(ctx context.Context) ([]repository.Account, error) {
+	return s.repo.GetAccounts(ctx)
+}
+
+// GetBalanceSheet returns a simplified balance sheet
+func (s *FinanceService) GetBalanceSheet(ctx context.Context) (map[string]interface{}, error) {
+	accounts, err := s.repo.GetAccounts(ctx)
+	if err != nil {
+		return nil, err
+	}
+
+	var assets, liabilities, equity float64
+	for _, a := range accounts {
+		switch a.Type {
+		case "asset":
+			assets += a.Balance
+		case "liability":
+			liabilities += a.Balance
+		case "equity":
+			equity += a.Balance
+		}
+	}
+
+	return map[string]interface{}{
+		"assets":      assets,
+		"liabilities": liabilities,
+		"equity":      equity,
+		"accounts":    accounts,
+	}, nil
+}