fix(simulation): route atlas_response fixtures in the serialize test

all_fixtures_deserialize panicked with "unknown fixture naming
convention: atlas_response_ready" — the test reads every .msgpack in
client/tests/fixtures/msgpack but had no branch for the atlas_response
prefix (the AtlasLayerResponse fixtures gen_fixtures emits, #969). A
pre-existing gap (present on main; the suite isn't gated by the pre-push
hook, which runs cargo-deny/ruff/JSON/stamp, not cargo test).

Add an atlas_response branch deserializing AtlasLayerResponse, and
regenerate atlas_response_ready.msgpack so its bytes match the now-integer
GeographicAttractor types (#955).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

server/tests/serialization.rs

@@ -1,5 +1,6 @@
 //! IPC serialization round-trip tests (D-030 Layer 1: fixture-based).
 
+use settled_reach_server::atlas::layer_proxy::AtlasLayerResponse;
 use settled_reach_server::bridge::types::*;
 use settled_reach_server::simulation::time::{DayPhase, TickRate};
 use std::fs;
@@ -173,6 +174,10 @@ fn all_fixtures_deserialize() {
             rmp_serde::from_slice::<ObserverSnapshot>(&bytes).unwrap_or_else(|e| {
                 panic!("deserialize boundary snapshot fixture {}: {}", name, e)
             });
+        } else if name.starts_with("atlas_response") {
+            // Atlas layer-stream responses (#969, D-225) — Ready/Pending/NotFound.
+            rmp_serde::from_slice::<AtlasLayerResponse>(&bytes)
+                .unwrap_or_else(|e| panic!("deserialize atlas_response fixture {}: {}", name, e));
         } else if name.starts_with("snapshot") {
             rmp_serde::from_slice::<ObserverSnapshot>(&bytes)
                 .unwrap_or_else(|e| panic!("deserialize snapshot fixture {}: {}", name, e));