fix: treat NotFound from read_schema as SpiceDB ready in integration tests

SpiceDB returns NotFound ('No schema has been defined') when it's
serving but has no schema written yet. The readiness check was treating
this as a failure, causing all integration tests to fail after retries.

Now the readiness probe accepts both Ok and NotFound as indicators
that SpiceDB is up and serving gRPC requests.

Author: rawkode

tests/integration.rs

@@ -86,10 +86,16 @@ async fn spicedb() -> Arc<SharedSpiceDb> {
                 for _ in 0..30 {
                     match Client::new(&endpoint, SPICEDB_TOKEN).await {
                         Ok(c) => match c.read_schema().await {
+                            // Schema read succeeded — SpiceDB is ready
                             Ok(_) => {
                                 result = Some(c);
                                 break;
                             }
+                            // NotFound means SpiceDB is serving but has no schema yet — that's ready
+                            Err(ref e) if e.code() == Some(tonic::Code::NotFound) => {
+                                result = Some(c);
+                                break;
+                            }
                             Err(e) => {
                                 last_err = Some(format!("{e}"));
                                 tokio::time::sleep(std::time::Duration::from_millis(200)).await;