refactor!: one way to serve books: the stdio server is gone (D-44)

The owner (2026-10-23): "We should probably just delete the stdio path
altogether. THere's no point in that. And it sitting there unused will
just lead to bitrot. Nuke it?"

Books are served only by the books server (`wanderbooks server`),
reached by agents through the bridge (`wanderbooks mcp --book ID`),
which stays.

Removed: `wanderbooks dev-stdio`, the `ledger-mcp` binary, and
`ledger_mcp::run` (stdio and `--http` over a bare data dir), with all
that only that mode had:
- files the books make coming back inline: `HandedFile.content_base64`
  is gone, and `download` and `expires_at` are always there;
- books with no access log or backups: `books.access_log`,
  `books.backup` and `books.back_up_now` are always offered, by scope;
- the settings file read and reloaded (`legacy_files`), the vault key
  named by a file or `--vault-key-file`, and the books dir's
  key-inside-the-books and git checks (with `paths.rs`);
- `wire.rs` (the bridge frames an agent's lines itself);
- `books.settings`' file fields and `books.start`'s `settings_source`.

`BooksServer` is built one way, from `Served` (a book as the books
server serves it), in production and in the unit tests. An unknown tool
is now a protocol error (mcp-tools.md). Inline file input is unchanged.

Then the owner's three decisions (2026-10-23, the question tool):
(a) `books.import_settings` is removed entirely (118 tools): old books
come in whole by `wanderbooks books adopt`, which reads their settings
file once; ledger-config keeps its settings-file parsing only as far as
adoption uses it (`load` and the path-reading `effective_receipt_policy`
are gone), and `books.chart_template` gives its settings as
`books.set_setting` changes. (b) The viewer's loose-books-folder mode is
removed (`--data-dir`, `--books-toml`, `--vault-key-file`, the settings
file and config.json followed): it opens only books of the data root,
reading settings from the journal and the vault from the book's own
`vault/` and `keys/`. (c) `wanderbooks dev-stdio` has no stub: it is an
unknown command like any other word. Also: an upload's expiry past the
calendar is an error, never an empty string.

Tests: every suite that drove the stdio server moved to
crates/ledger-cli/tests/ and drives a real `wanderbooks server` on a
data root of its own (tests/common), handed files by their download;
mcp_stdio.rs is mcp_journeys.rs. Tests of what is gone are deleted and
listed in docs/testing.md. Docs: plan D-44 (D-18 superseded), STATUS,
testing, rules, mcp-interface, the handbook, README; justfile recipes.

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

docs/architecture.md

@@ -114,12 +114,13 @@ engine keeps them beside the ledger (`ledger_core::settings::Settings`,
 its replay and the viewer's `Snapshot` share one reading; `Ledger::
 differs_from` and `verify` compare them, and the projection has a table
 for each (schema v12). `ledger-config` is the codec between them and a
-`wanderbooks.toml` (`codec::import`, `codec::export`) and still reads the
-file for books that predate P1 (the "file" source, until
-`books.import_settings`). The server (`settings::Live`) takes the books'
-settings whenever their last `settings.set` changes (on every lock of the
-store) and then never reads a file; "today" is the company's time zone's,
-set per request. Rule: `docs/spec/rules.md` B-29.
+`wanderbooks.toml` (`codec::import`, `codec::export`): adoption (`wanderbooks
+books adopt`) moves an older books dir's file in through it, once, and
+`books.export_settings` writes the books' settings out as one. The books
+are their settings' only source (D-44): the server (`settings::Live`)
+takes them whenever their last `settings.set` changes (on every lock of
+the store), the viewer reads them from the journal it shows, and neither
+reads a file; "today" is the company's time zone's, set per request. Rule: `docs/spec/rules.md` B-29.
 
 ## The MCP server's store lock (`ledger-mcp`, P0)