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_test.go

@@ -83,8 +83,9 @@ func TestCorpusIdempotentAndSafe(t *testing.T) {
 
 // semanticallyEqual compares the non-trivia token streams of two sources,
 // treating unquoted identifiers/keywords case-insensitively and everything
-// else (strings, numbers, dollar bodies, operators, punctuation) exactly. This
-// validates that formatting changed only layout/casing, never meaning.
+// else (strings, numbers, operators, punctuation) exactly. Dollar-quoted body
+// tokens are compared recursively so body whitespace normalization does not
+// trigger a false failure.
 func semanticallyEqual(a, b string) bool {
 	ta := significant(a)
 	tb := significant(b)
@@ -95,12 +96,21 @@ func semanticallyEqual(a, b string) bool {
 		if ta[i].Kind != tb[i].Kind {
 			return false
 		}
-		if ta[i].Kind == lexer.Ident {
+		switch ta[i].Kind {
+		case lexer.Ident:
 			if !strings.EqualFold(ta[i].Text, tb[i].Text) {
 				return false
 			}
-		} else if ta[i].Text != tb[i].Text {
-			return false
+		case lexer.DollarString:
+			_, innerA, _, okA := splitDollarQuote(ta[i].Text)
+			_, innerB, _, okB := splitDollarQuote(tb[i].Text)
+			if okA != okB || (okA && !semanticallyEqual(innerA, innerB)) {
+				return false
+			}
+		default:
+			if ta[i].Text != tb[i].Text {
+				return false
+			}
 		}
 	}
 	return true