Use avro for datafiles collection from write-exec

AGENTS.md

@@ -82,7 +82,7 @@ input
  → project_with_partition  partitioned tables only: appends a `_partition` struct column computed by `PartitionExpr`
  → repartition             hash on `_partition` for identity/bucket transforms, otherwise round-robin; uses session target_partitions
  → sort_by_partition       only when table property `write.datafusion.fanout.enabled` is false (default: true)
- → IcebergWriteExec        per partition: `TaskWriter` writes Parquet files and emits JSON-serialized DataFiles in a `data_files` column
+ → IcebergWriteExec        per partition: `TaskWriter` writes Parquet files and emits Avro-serialized DataFiles in a `data_files: LargeBinary` column
  → CoalescePartitionsExec
  → IcebergCommitExec       single partition: one `fast_append` transaction; outputs a `count` row
 ```

Cargo.toml

@@ -37,8 +37,8 @@ datafusion = "55.0.0"
 datafusion-cli = "55.0.0"
 iceberg-datafusion = { path = "crates/datafusion" }
 datafusion-sqllogictest = "55.0.0"
-iceberg = { git = "https://github.com/apache/iceberg-rust", rev = "8cb2adeddb4f8da1ca7bd86ca303337f011c12e2" }
-iceberg-catalog-rest = { git = "https://github.com/apache/iceberg-rust", rev = "8cb2adeddb4f8da1ca7bd86ca303337f011c12e2" }
+iceberg = { git = "https://github.com/apache/iceberg-rust", rev = "5b82ab99aeaf50bf4f5b3b776ac9cd6380a5f3e3" }
+iceberg-catalog-rest = { git = "https://github.com/apache/iceberg-rust", rev = "5b82ab99aeaf50bf4f5b3b776ac9cd6380a5f3e3" }
 tokio = { version = "1.47", default-features = false, features = ["sync", "rt-multi-thread"] }
 toml = "1.1"
 tracing = "0.1.41"

crates/datafusion/src/table_provider/catalog_table_provider.rs

@@ -605,7 +605,7 @@ mod tests {
     async fn get_partitioned_test_catalog_and_table(
         fanout_enabled: Option<bool>,
     ) -> (Arc<dyn Catalog>, NamespaceIdent, String, TempDir) {
-        use iceberg::spec::{Transform, UnboundPartitionSpec};
+        use iceberg::spec::{Transform, UnboundPartitionField, UnboundPartitionSpec};
 
         let temp_dir = TempDir::new().unwrap();
         let warehouse_path = temp_dir.path().to_str().unwrap().to_string();
@@ -644,7 +644,14 @@ mod tests {
 
         let partition_spec = UnboundPartitionSpec::builder()
             .with_spec_id(0)
-            .add_partition_field(2, "category", Transform::Identity)
+            .add_partition_field(
+                UnboundPartitionField::builder()
+                    .source_ids(vec![2])
+                    .name("category")
+                    .transform(Transform::Identity)
+                    .build()
+                    .unwrap(),
+            )
             .unwrap()
             .build();