Refactored the application structure to better separate concerns between files and packages

internal/adapters/outbound/postgres/scan_helpers.go

@@ -0,0 +1,39 @@
+// scan_helpers.go provides shared sql.Null* conversion helpers.
+// Layer: adapters/outbound/postgres helper utilities.
+package postgres
+
+import (
+	"database/sql"
+	"time"
+)
+
+func stringValue(v sql.NullString) string {
+	if !v.Valid {
+		return ""
+	}
+	return v.String
+}
+
+func boolPtr(v sql.NullBool) *bool {
+	if !v.Valid {
+		return nil
+	}
+	b := v.Bool
+	return &b
+}
+
+func float64Ptr(v sql.NullFloat64) *float64 {
+	if !v.Valid {
+		return nil
+	}
+	f := v.Float64
+	return &f
+}
+
+func timePtr(v sql.NullTime) *time.Time {
+	if !v.Valid {
+		return nil
+	}
+	t := v.Time.UTC()
+	return &t
+}