feat(rust): RunicNPC is required in the Rust bundle (runicnpc stage 9, D310)

- install/update refuse a Rust bundle that carries no RunicNPC, before anything
  is written, and say how to get one that does.
- doctor fails when RunicNPC is missing or was never installed; a file edited
  by hand stays a warning, since it still loads.
- compose-bundles.sh composes no Rust bundle without a RunicNPC release that
  answers the bridge's runicnpc_api (the published one stays), and fails a
  bridge that declares none; every Rust bundle now has `npc`.
- A RunicNPC API-mismatch message lost its line continuation; restored.

The bundle type still parses a bundle without `npc`, so doctor and an old pin
can name it.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01E14m6SuuY6i1vASFeGDBeY

src/rustgame/npc.rs

@@ -8,8 +8,9 @@
 //! it. RunicNPC makes that directory itself on first load, because one made from outside the game
 //! is not writable by it (runicnpc PLAN.md §1.5).
 //!
-//! It is optional until RunicNPC's stage 9: a bundle without it installs as before, and a host
-//! without it runs the bridge with Rust's own scientists only (D243).
+//! It is required since RunicNPC's stage 9 (D310): the bridge refuses every NPC an event places
+//! without it, Rust's own scientists included, so `install` and `update` refuse a bundle that does
+//! not carry it and `doctor` fails a host that lacks it.
 
 use std::collections::BTreeMap;
 use std::io::Read;