test(host): a books home's files are listed with one separator on every OS

P11c run 7 on Windows: the walk spelled `.claude\settings.json`.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HS8WZziDnyxunC23MUxrLp

crates/ledger-host/tests/books_home.rs

@@ -14,7 +14,13 @@ fn names(dir: &Path) -> Vec<String> {
             if p.is_dir() {
                 walk(base, &p, out);
             } else {
-                out.push(p.strip_prefix(base).unwrap().to_string_lossy().into_owned());
+                // One spelling on every OS (Windows walks with backslashes).
+                out.push(
+                    p.strip_prefix(base)
+                        .unwrap()
+                        .to_string_lossy()
+                        .replace('\\', "/"),
+                );
             }
         }
     }