fix: Windows reads of lock files, update paths cfg(unix), merge main again (P11c)

spec_vault swept every file under a book, lock files included; on Windows
a held LockFileEx lock is mandatory and the read failed. The locks are
already dedicated files (never data), so the test skips *.lock. Merged
main (P13 step 6, the macOS server.log assert, P11a's AppImage identity):
host.rs keeps main's five-field identity on Unix and size/last-write on
Windows; the update poll and set_program_version are Unix-only.

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

crates/ledger-cli/tests/spec_vault.rs

@@ -521,6 +521,9 @@ fn files_under(dir: &Path) -> Vec<PathBuf> {
         let p = e.path();
         if p.is_dir() {
             out.extend(files_under(&p));
+        } else if p.extension().is_some_and(|x| x == "lock") {
+            // A lock file holds no data, and on Windows a held lock is
+            // mandatory: reading it is refused while the server runs.
         } else {
             out.push(p);
         }