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

.gitea/workflows/bundle.yml

@@ -19,7 +19,7 @@
 #   current.json, bundle-<tag>.json              schema 1, ServUO: link + overlay
 #   v2/servuo/current.json, bundle-<tag>.json    schema 2, game "servuo"
 #   v2/rust/current.json, bundle-<tag>.json      schema 2, game "rust": Rust-Link + Rust-Plugins,
-#                                                and RunicNPC when the bridge needs it (D224)
+#                                                and RunicNPC, required since its stage 9 (D224, D310)
 #
 # Schema 2 (D146) names ONE game, with a `game` discriminant and a `payload`
 # that is an overlay for ServUO and a plugin for Rust. Schema 1 (D147) is still