P2 slice 6: the viewer

`wanderbooks gui [BOOK]` finds the data root, reads settings from the
journal, the vault of the book, presence through ops/, Save a copy /
Open on every document, Save the W-9, the Export menu, and colour
schemes. One builder for the CPA package and the 1099 worksheet
(ledger-package), shared by the server and the viewer.

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

crates/ledger-gui/tests/show.rs

@@ -3,7 +3,7 @@
 use egui_kittest::Harness;
 use ledger_gui::nav::{ReportKind, Route};
 use ledger_gui::{App, Source, data};
-use ledger_store::viewer::ViewerTarget;
+use ledger_store::ops::ViewerTarget;
 
 /// A test's dir, removed when the test ends, pass or panic.
 struct TestDir(std::path::PathBuf);
@@ -23,7 +23,6 @@ fn show_requests_navigate_the_viewer() {
     ledger_gui::demo::build(&dir, today).unwrap();
     let source = Source {
         data_dir: dir.join("books-data"),
-        books_toml: Some(dir.join("wanderbooks.toml")),
         today: Some(today),
     };
     let books = data::load_once(&source).unwrap();