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

justfile

@@ -32,10 +32,10 @@ site-shots:
     #!/usr/bin/env bash
     set -euo pipefail
     tmp=$(mktemp -d)
-    SHOT_DIR="$tmp" SHOT_DARK=1 SHOT_LIVE=1 SHOT_ONLY=overview,pnl cargo test -p ledger-gui --test screens
+    SHOT_DIR="$tmp" SHOT_DARK=1 SHOT_LIVE=1 SHOT_ONLY=overview,pnl,cash cargo test -p ledger-gui --test screens
     # The hero's viewer pane: taller, to sit beside the session.
     SHOT_DIR="$tmp" SHOT_DARK=1 SHOT_LIVE=1 SHOT_ONLY=entry SHOT_ENTRY=245 SHOT_HEIGHT=1150 cargo test -p ledger-gui --test screens
-    for f in overview entry pnl; do cp "$tmp/$f.png" site/assets/; done
+    for f in overview entry pnl cash; do cp "$tmp/$f.png" site/assets/; done
     rm -f site/assets/overview-dark.png
     rm -rf "$tmp"