Add CTEType handling to FROM clause rewriting

The FROM clause rewriter had no case for CTEType, causing CTE references
to hit the default error case "unknown indirect type".

CTEs are now handled like views - the inner SELECT is executed and
wrapped with the CTE name as an alias: ( inner_select ) AS "cte_name"

Author: claude

internal/stackql/astvisit/from_rewrite.go

@@ -671,6 +671,12 @@ func (v *standardFromRewriteAstVisitor) Visit(node sqlparser.SQLNode) error {
 					templateString := ` ( %s ) `
 					v.rewrittenQuery = templateString
 					v.indirectContexts = append(v.indirectContexts, indirect.GetSelectContext())
+				case astindirect.CTEType:
+					// CTEs are handled like views - the inner SELECT is executed
+					// and results are wrapped with the CTE name as alias.
+					templateString := fmt.Sprintf(` ( %%s ) AS "%s" `, name)
+					v.rewrittenQuery = templateString
+					v.indirectContexts = append(v.indirectContexts, indirect.GetSelectContext())
 				case astindirect.MaterializedViewType, astindirect.PhysicalTableType:
 					refString := fmt.Sprintf(` %s `, name)
 					isQuoted, _ := regexp.MatchString(`^".*"$`, name)