feat: books.show — the agent puts things on the viewer's screen

books.show asks the viewer to open an entry, an account register, a
report (dates, month/quarter/year columns, prior-period or prior-year
comparison), a document, a search, or a page. The request lives outside
the books (runtime dir, keyed by data dir, written atomically); the
viewer watches it beside the journal and applies books before
navigating. 66 tools.

Site: the dashboard is the hero again; 'Here's what using it looks like'
shows the session beside the viewer, ending in books.show; the cash page
replaces the repeated overview lower down.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MtYEaR6M6Ybdhm6X98BWNu

crates/ledger-cli/src/main.rs

@@ -173,6 +173,10 @@ Bank feeds aren't automatic here: import the bank's CSV export
 
 - Every transaction: draft, preview, confirm with the human, post, attach
   the receipt. Tag payments to contractors with their vendor (1099s).
+- The human usually has the viewer open beside you (`just gui`). When they
+  ask to see something, and after you post, put it on their screen with
+  `books.show` (an entry, an account register, a report, a document, or a
+  search).
 - `books.digest` is the review surface — "what did you do with my books
   lately." Offer it; don't make the human ask.
 - Reports are pure functions of the journal. If a number looks wrong, the