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

plan/STATUS.md

@@ -296,3 +296,9 @@ interface is MCP, not a cloned GUI. The first storage + MCP slice is done
   the CPA (package, read-only clone + GUI). The site leads with owning
   your books and an AI bookkeeper: example prompts, a QuickBooks
   comparison, an honest "what it doesn't do yet", the CPA section, FAQ.
+- 2026-10-12: The agent can drive the viewer. books.show (66 tools) asks
+  the viewer to open an entry, account register, report (with dates),
+  document, search, or page. The request lives outside the books (a JSON
+  file in the runtime dir keyed by the data dir, written atomically); the
+  viewer watches it beside the journal and applies books before
+  navigation. ~30 ms end to end.