Phase 1: storage + catalog layer

- storaged: object_store backend (LocalFileSystem), PUT/GET/DELETE/LIST endpoints
- shared: arrow_helpers with Parquet roundtrip + schema fingerprinting (2 tests)
- catalogd: in-memory registry with write-ahead manifest persistence to object storage
- catalogd: POST/GET /datasets, GET /datasets/by-name/{name}
- gateway: wires storaged + catalogd with shared object_store state
- Phase tracker updated: Phase 0 + Phase 1 gates passed

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

crates/gateway/src/main.rs

@@ -9,10 +9,20 @@ async fn main() {
         .with(fmt::layer())
         .init();
 
+    // Storage backend — local filesystem for now
+    let storage_root = std::env::var("STORAGE_ROOT").unwrap_or_else(|_| "./data".to_string());
+    let store = storaged::backend::init_local(&storage_root);
+
+    // Catalog — rebuild from persisted manifests
+    let registry = catalogd::registry::Registry::new(store.clone());
+    if let Err(e) = registry.rebuild().await {
+        tracing::warn!("catalog rebuild failed (empty store?): {e}");
+    }
+
     let app = Router::new()
         .route("/health", get(health))
-        .nest("/storage", storaged::service::router())
-        .nest("/catalog", catalogd::service::router())
+        .nest("/storage", storaged::service::router(store))
+        .nest("/catalog", catalogd::service::router(registry))
         .nest("/query", queryd::service::router())
         .nest("/ai", aibridge::service::router())
         .layer(TraceLayer::new_for_http());