feat(format): add PL/pgSQL body formatting and tests

* Implemented formatting for BEGIN...END blocks in PL/pgSQL.
* Added logic to handle indentation and blank lines.
* Introduced tests for broken formatting cases.

pkg/format/format_test.go

@@ -49,6 +49,28 @@ func TestIdempotentSmall(t *testing.T) {
 	}
 }
 
+func TestFormatBodyBroken(t *testing.T) {
+	dir := filepath.Join("..", "..", "testdata", "corpus")
+	brokenData, err := os.ReadFile(filepath.Join(dir, "test_a_broken.pgsql"))
+	if err != nil {
+		t.Skipf("no test_a_broken.pgsql: %v", err)
+	}
+	goldenData, err := os.ReadFile(filepath.Join(dir, "test_a.pgsql"))
+	if err != nil {
+		t.Skipf("no test_a.pgsql: %v", err)
+	}
+
+	got := format(string(brokenData))
+	want := string(goldenData)
+	if got != want {
+		t.Errorf("format(test_a_broken) != test_a.pgsql\n--- got ---\n%s\n--- want ---\n%s", got, want)
+	}
+	twice := format(got)
+	if twice != got {
+		t.Errorf("format(test_a_broken) is not idempotent")
+	}
+}
+
 func TestCorpusIdempotentAndSafe(t *testing.T) {
 	dir := filepath.Join("..", "..", "testdata", "corpus")
 	entries, err := os.ReadDir(dir)