Phase 2: DataFusion query engine over Parquet

- queryd: SessionContext with custom URL scheme to avoid path doubling with LocalFileSystem
- queryd: ListingTable registration from catalog ObjectRefs with schema inference
- queryd: POST /query/sql returns JSON {columns, rows, row_count}
- queryd→catalogd wiring: reads all datasets, registers as named tables
- gateway: wires QueryEngine with shared store + registry
- e2e verified: SELECT *, WHERE/ORDER BY, COUNT/AVG all correct

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

crates/queryd/Cargo.toml

@@ -5,8 +5,16 @@ edition = "2024"
 
 [dependencies]
 shared = { path = "../shared" }
+catalogd = { path = "../catalogd" }
+storaged = { path = "../storaged" }
 tokio = { workspace = true }
 axum = { workspace = true }
 serde = { workspace = true }
 serde_json = { workspace = true }
 tracing = { workspace = true }
+datafusion = { workspace = true }
+object_store = { workspace = true }
+arrow = { workspace = true }
+bytes = { workspace = true }
+futures = { workspace = true }
+url = { workspace = true }