P1: the books keep how they are kept

Settings, conventions (posting templates, approval rules, policies,
close steps, calendar, mappings, notes), decisions, open items and
entry approvals are journal events (journal format 2). Books that keep
their settings never read wanderbooks.toml or config.json; the server
and the viewer take the vault key from --vault-key-file instead.
books.import_settings moves a settings file in once, exactly as the
server reads it. Approval rules, when enforced, gate every posting
path. Replay refuses what it can't read as newer, never as corrupt.

Lean: a record changes no figure. Mutation on the whole diff: every
survivor killed by a test but two equivalent (docs/testing.md). The
Company page says a late open item is overdue in words, not colour
alone.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01T3gXMVt7XJPi6ens1or9Dj

crates/ledger-gui/src/lib.rs

@@ -22,3 +22,18 @@ mod widgets;
 
 pub use app::App;
 pub use data::Source;
+
+/// The vault key file named on the command line (`--vault-key-file`),
+/// which wins over a settings file's `[vault] key_file`, as it does for
+/// the server: books that keep their own settings never name it.
+static VAULT_KEY_FILE: std::sync::OnceLock<std::path::PathBuf> = std::sync::OnceLock::new();
+
+/// Name the vault key file (once, at start).
+pub fn set_vault_key_file(path: std::path::PathBuf) {
+    let _ = VAULT_KEY_FILE.set(path);
+}
+
+/// The vault key file named on the command line, if one was.
+pub fn vault_key_file() -> Option<std::path::PathBuf> {
+    VAULT_KEY_FILE.get().cloned()
+}