fix(writer): update nullable type handling to use baselib

* change default nullable type from resolvespec to baselib
* update type mappings in tests to reflect new nullable types
* adjust comments for clarity on nullable type options

pkg/writers/gorm/writer_test.go

@@ -70,7 +70,7 @@ func TestWriter_WriteTable(t *testing.T) {
 		"ID",
 		"int64",
 		"Email",
-		"sql_types.SqlString",
+		"*string",
 		"CreatedAt",
 		"time.Time",
 		"gorm:\"column:id",
@@ -700,17 +700,17 @@ func TestTypeMapper_SQLTypeToGoType(t *testing.T) {
 		want    string
 	}{
 		{"bigint", true, "int64"},
-		{"bigint", false, "sql_types.SqlInt64"},
+		{"bigint", false, "*int64"},
 		{"varchar", true, "string"},
-		{"varchar", false, "sql_types.SqlString"},
+		{"varchar", false, "*string"},
 		{"timestamp", true, "time.Time"},
-		{"timestamp", false, "sql_types.SqlTimeStamp"},
+		{"timestamp", false, "*time.Time"},
 		{"boolean", true, "bool"},
-		{"boolean", false, "sql_types.SqlBool"},
-		{"text[]", true, "sql_types.SqlStringArray"},
-		{"text[]", false, "sql_types.SqlStringArray"},
-		{"integer[]", true, "sql_types.SqlInt32Array"},
-		{"bigint[]", false, "sql_types.SqlInt64Array"},
+		{"boolean", false, "*bool"},
+		{"text[]", true, "[]string"},
+		{"text[]", false, "[]string"},
+		{"integer[]", true, "[]int32"},
+		{"bigint[]", false, "[]int64"},
 	}
 
 	for _, tt := range tests {