fix(pgsql): handle default values for array types in migrations

* update default value quoting logic for PostgreSQL
* add tests for array default value handling

pkg/writers/writer_test.go

@@ -0,0 +1,54 @@
+package writers
+
+import "testing"
+
+func TestQuoteDefaultValue(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name    string
+		value   string
+		sqlType string
+		want    string
+	}{
+		{
+			name:    "text default is quoted",
+			value:   "active",
+			sqlType: "text",
+			want:    "'active'",
+		},
+		{
+			name:    "array default from bare literal is quoted once",
+			value:   "{}",
+			sqlType: "text[]",
+			want:    "'{}'",
+		},
+		{
+			name:    "array default from quoted literal is preserved",
+			value:   "'{}'",
+			sqlType: "text[]",
+			want:    "'{}'",
+		},
+		{
+			name:    "array default from double quoted literal is normalized",
+			value:   "''{}''",
+			sqlType: "text[]",
+			want:    "'{}'",
+		},
+		{
+			name:    "function default is left alone",
+			value:   "now()",
+			sqlType: "timestamptz",
+			want:    "now()",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := QuoteDefaultValue(tt.value, tt.sqlType)
+			if got != tt.want {
+				t.Fatalf("QuoteDefaultValue(%q, %q) = %q, want %q", tt.value, tt.sqlType, got, tt.want)
+			}
+		})
+	}
+}