feat(format): implement PL/pgSQL body formatting

* add formatBody and formatBodyInner functions for DECLARE section
* update needSpace to handle LBracket correctly
* enhance semanticallyEqual to compare dollar-quoted bodies
* add test data for broken layout scenarios

pkg/format/format.go

@@ -104,7 +104,7 @@ func (p *printer) writeCreateFunction(cf *cst.CreateFunction) {
 	}
 	if cf.Body != nil {
 		p.nl()
-		p.b.WriteString(cf.Body.Tok.Text) // body emitted verbatim (formatted later)
+		p.b.WriteString(formatBody(cf.Body.Tok.Text, p.st))
 	}
 	for _, clause := range cf.Tail {
 		p.nl()
@@ -179,6 +179,11 @@ func needSpace(a, b lexer.Token) bool {
 		case lexer.Ident, lexer.QuotedIdent, lexer.RParen, lexer.RBracket, lexer.Param:
 			return false // function call / type modifier
 		}
+	case lexer.LBracket:
+		switch a.Kind {
+		case lexer.Ident, lexer.QuotedIdent, lexer.RParen, lexer.RBracket:
+			return false // array subscript / array type modifier
+		}
 	case lexer.Operator:
 		if tightOps[b.Text] {
 			return false