P0: pin dev tools, honest transports doc, tools-only template

mise.toml: pin cargo-mutants 27.1.0 and cargo-fuzz 0.13.2 (the latest
published, and what is installed) instead of "latest", so mutation and
fuzz runs repeat (plan/served.md I-13, P0).

docs/mcp-interface.md: the spec had two Transports sections, and the
first claimed bearer-token auth on Streamable HTTP. There is none: the
server uses rmcp's default config, whose only guard is a Host check for
localhost, 127.0.0.1 and ::1, with no token and no Origin check. One
section now says so plainly and points to plan/served.md P2 for auth.

ledger-cli AGENTS.md template: "the journal is the evidence - read it,
don't guess" led an agent to cat the journal file instead of asking the
books. The template now says to trace a figure through books.get_entry,
books.search_entries, or books.export (journal or general_ledger), and a
new bullet says the books are reached only through the wanderbooks MCP
tools: never open, list or parse the books' files, not even to look; if
a tool can't answer, say so. The other lines that sent the agent to the
data dir go too: onboarding is triggered by an empty books.chart instead
of a missing journal.jsonl, the CPA paragraph drops the ledger-gui
--data-dir books-data command, and the backup note no longer names the
journal's path. Test agents_md_reaches_the_books_only_through_tools
pins this; agents_md_carries_the_contract no longer expects journal.jsonl.

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

mise.toml

@@ -18,5 +18,5 @@ node = "26"
 # verify/lean/lean-toolchain.
 "github:leanprover/lean4" = "4.34.1"
 # Mutation testing and fuzzing (docs/oracle.md).
-"cargo:cargo-mutants" = "latest"
-"cargo:cargo-fuzz" = "latest"
+"cargo:cargo-mutants" = "27.1.0"
+"cargo:cargo-fuzz" = "0.13.2"