Fix tuple rendering when containing array literals

When a tuple contains array literals, render as Function tuple format
instead of Literal Tuple_ format. This matches ClickHouse's EXPLAIN AST
output which shows tuples with arrays as:
  Function tuple (alias a) (children 1)
   ExpressionList (children 2)
    Literal UInt64_456
    Literal Array_[...]

Fixes 3 statements in 00300_csv.

Author: claude

internal/explain/expressions.go

@@ -478,8 +478,13 @@ func explainAliasedExpr(sb *strings.Builder, n *ast.AliasedExpr, depth int) {
 						needsFunctionFormat = true
 						break
 					}
-					// Also check if nested arrays/tuples contain non-literal elements
+					// Check if tuple contains array literals - these need Function tuple format
 					if lit, ok := expr.(*ast.Literal); ok {
+						if lit.Type == ast.LiteralArray {
+							needsFunctionFormat = true
+							break
+						}
+						// Also check if nested arrays/tuples contain non-literal elements
 						if containsNonLiteralInNested(lit) {
 							needsFunctionFormat = true
 							break

parser/testdata/00300_csv/metadata.json

@@ -1,7 +1,2 @@
 {
-  "explain_todo": {
-    "stmt1": true,
-    "stmt2": true,
-    "stmt3": true
-  }
 }