feat: wire durable assignments into API

server/api/store_adapters_test.go

@@ -0,0 +1,17 @@
+package api
+
+import (
+	"context"
+	"testing"
+	"time"
+)
+
+func TestAssignmentProviderFromStorePreservesPlayerScopedRecoveryBoundary(t *testing.T) {
+	provider := AssignmentProviderFromStore(nil)
+	if provider == nil {
+		t.Fatal("store provider was not created")
+	}
+	if _, err := provider(context.Background(), "player-1", "match-1", time.Unix(1000, 0)); err == nil {
+		t.Fatal("nil store was treated as an available assignment source")
+	}
+}