Fix explain output formatting and test comparison

- Strip server error messages from expected explain output
- Fix CreateQuery spacing for CREATE DATABASE (add extra space)
- Fix DropQuery spacing for DROP DATABASE vs DROP TABLE

This fixes 243 tests (5606 -> 5849 passing).

Author: claude

internal/explain/statements.go

@@ -62,7 +62,12 @@ func explainCreateQuery(sb *strings.Builder, n *ast.CreateQuery, indent string,
 	if n.AsSelect != nil {
 		children++
 	}
-	fmt.Fprintf(sb, "%sCreateQuery %s (children %d)\n", indent, name, children)
+	// ClickHouse adds an extra space before (children N) for CREATE DATABASE
+	if n.CreateDatabase {
+		fmt.Fprintf(sb, "%sCreateQuery %s  (children %d)\n", indent, name, children)
+	} else {
+		fmt.Fprintf(sb, "%sCreateQuery %s (children %d)\n", indent, name, children)
+	}
 	fmt.Fprintf(sb, "%s Identifier %s\n", indent, name)
 	if len(n.Columns) > 0 {
 		fmt.Fprintf(sb, "%s Columns definition (children %d)\n", indent, 1)
@@ -154,7 +159,12 @@ func explainDropQuery(sb *strings.Builder, n *ast.DropQuery, indent string) {
 	if n.DropDatabase {
 		name = n.Database
 	}
-	fmt.Fprintf(sb, "%sDropQuery  %s (children %d)\n", indent, name, 1)
+	// DROP DATABASE uses different spacing than DROP TABLE
+	if n.DropDatabase {
+		fmt.Fprintf(sb, "%sDropQuery %s  (children %d)\n", indent, name, 1)
+	} else {
+		fmt.Fprintf(sb, "%sDropQuery  %s (children %d)\n", indent, name, 1)
+	}
 	fmt.Fprintf(sb, "%s Identifier %s\n", indent, name)
 }
 

parser/parser_test.go

@@ -118,6 +118,11 @@ func TestParser(t *testing.T) {
 			explainPath := filepath.Join(testDir, "explain.txt")
 			if expectedBytes, err := os.ReadFile(explainPath); err == nil {
 				expected := strings.TrimSpace(string(expectedBytes))
+				// Strip server error messages from expected output
+				// These are messages like "The query succeeded but the server error '43' was expected..."
+				if idx := strings.Index(expected, "\nThe query succeeded but the server error"); idx != -1 {
+					expected = strings.TrimSpace(expected[:idx])
+				}
 				actual := strings.TrimSpace(parser.Explain(stmts[0]))
 				if actual != expected {
 					if metadata.Todo {