fix(cmd): handle errors and improve output formatting

* update error handling in various commands to use blank identifier
* enhance output formatting for better readability
* add golangci-lint to Makefile for linting checks

pkg/format/dml.go

@@ -10,16 +10,13 @@ import (
 
 // isDMLStart reports whether toks begins with a DML statement keyword.
 func isDMLStart(toks []cst.Tok) bool {
-	for _, t := range toks {
-		if t.Tok.Kind == lexer.Ident {
-			switch lowerASCII(t.Tok.Text) {
-			case "select", "insert", "update", "delete", "with":
-				return true
-			}
-			return false
-		}
+	if len(toks) == 0 || toks[0].Tok.Kind != lexer.Ident {
 		return false
 	}
+	switch lowerASCII(toks[0].Tok.Text) {
+	case "select", "insert", "update", "delete", "with":
+		return true
+	}
 	return false
 }
 
@@ -510,13 +507,6 @@ func dmlSplitCommas(toks []cst.Tok) [][]cst.Tok {
 	return items
 }
 
-// dmlColList formats kwText followed by a comma-separated body.
-// One item: kept on the same line as the keyword.
-// Multiple items: each on its own line with the configured comma style.
-func dmlColList(kwText string, items [][]cst.Tok, st config.Style) string {
-	return dmlColListSelect(kwText, items, st)
-}
-
 // dmlColListSelect formats a SELECT / RETURNING column list with optional
 // align_columns and select_align_as settings.
 func dmlColListSelect(kwText string, items [][]cst.Tok, st config.Style) string {
@@ -627,7 +617,10 @@ func dmlColListSet(kwText string, items [][]cst.Tok, st config.Style) string {
 // alias names align vertically.
 func alignSelectItems(texts []string, st config.Style) []string {
 	// Split each text into (expr, " AS ", alias) or keep as-is.
-	type part struct{ expr, alias string; hasAs bool }
+	type part struct {
+		expr, alias string
+		hasAs       bool
+	}
 	parts := make([]part, len(texts))
 	maxExpr := 0
 	for i, t := range texts {