What One Rust Client Can Reach Across Seven Iceberg Catalogs

Step by step: the Apache Rust Iceberg REST client against seven Iceberg catalogs. It logs in to five of them, and on every one it logs in to, all 13 endpoints it implements answer — 7 reads on three catalogs and 11 writes on the local one, with no failures. The two AWS catalogs need SigV4, which it cannot send, so Rust reaches them through two other crates whose operation sets differ from its own.