Recover: each entry's age, and Discard all

file.recovery.list gives each entry's age; File › Recover shows name, age and counts, newest
first, with Discard all. docs/formats/fieldcraft.md states the folder and pruning rules.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UhhZMBTviDQxZvwnyP89fo

crates/engine/src/autosave.rs

@@ -84,6 +84,7 @@ mod tests {
         let listed = s.execute("file.recovery.list", &json!({"dir": dir})).unwrap();
         assert_eq!(listed[0]["id"], id);
         assert_eq!(listed[0]["nodes"], 1);
+        assert!(listed[0]["age"].as_u64().is_some_and(|a| a < 60), "{listed}");
         let mut next = Session::default();
         let r = next.execute("file.recover", &json!({"id": id, "dir": dir})).unwrap();
         assert_eq!(r["nodes"], 1);