feat: one-command onboarding — wanderbooks new, install.sh, justfile

wanderbooks new DIR installs the server and GUI if missing, writes the
books dir (AGENTS.md + CLAUDE.md, wanderbooks.toml, justfile, .mcp.json,
.claude/settings.json approving the server), commits, and starts claude
onboarding. install.sh: Rust + cargo install + wanderbooks new in one
line. The tax summary labels its net when accounts are uncategorized.

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

plan/STATUS.md

@@ -267,3 +267,10 @@ interface is MCP, not a cloned GUI. The first storage + MCP slice is done
   balance series and history, P&L by interval, flows), ledger-config
   (extracted from ledger-mcp; full profile, cash_accounts). Fonts: Inter
   with tnum frozen in and private-use glyphs removed (Phosphor icons).
+- 2026-10-12: One-command onboarding. `wanderbooks new DIR` installs the
+  server and GUI if missing, writes AGENTS.md (+ CLAUDE.md importing it),
+  wanderbooks.toml, a justfile (agent, gui, backup, update), .gitignore,
+  .mcp.json (the server registered for that dir only) and
+  .claude/settings.json (approved, no prompt), commits, and starts claude
+  with the onboarding prompt. `install.sh` does Rust + cargo install +
+  `wanderbooks new` in one line. mise is no longer part of the scaffold.