R3.1: real paths without \?\ on Windows (dunce); old recent lists read plain

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

crates/ely-files/src/session/registry.rs

@@ -83,7 +83,7 @@ impl Sessions {
     /// The key of an existing file; missing fails loud.
     fn key(path: &Path) -> io::Result<Key> {
         Ok(Key {
-            canonical: std::fs::canonicalize(path)?,
+            canonical: dunce::canonicalize(path)?,
             id: file_id(path)?,
         })
     }