feat(rust): Dangerous Treasures — feed, map, Treasure Hunter, Start a Dangerous Treasures event (PLAN_REDESIGNS §14.3.4)

Stage 5 of the §14.3 integration plan, on protocol 14 (docs
rust-link/PROTOCOL.md §20.8).

- dt.started and dt.won are public kinds, dt.ended a staff kind. The new
  dangerousTreasures.js reads each row per viewer: grid and invaderCount for
  everyone, the winner's name for the presence audience (D376), the position,
  the step's key, the winner's Steam id and the invaders for staff.
- Feed lines in the World events filter: "A Dangerous Treasures event has
  started · K12", "Alice won the treasure · K12 · 3 players fought for it".
- Triggers rust.dt.started (with byEvent) and rust.dt.won, public, cooldown
  subject the server, names only.
- eventDangerousTreasures.js: rust.dt.start, "Start a Dangerous Treasures
  event" (risk change, reversible none, budget rust.dt.events), server and
  difficulty. Refused at verify where the server said DT is not loaded or
  console.plugins is false (Rust-Plugins#34). dt-not-ready answers "Dangerous
  Treasures is not ready yet" with retryAfterMs 600000 (D365, D371);
  dt-no-spot retries on core's delay; DT's own refusals are permanent.
- Treasure Hunter (D375): treasuresWon -> treasures_won, the title category
  treasureswon, and a sortable Treasures column shown where the server
  reports DT or a row counts one.
- The map draws a running chest on the world layer; the server settings'
  plugin line names DT and whether a step can start one, from the
  integrations read's new `console`.
- coreApi ^1.15.0, ci/core-ref.json pinned to website main at #215's merge.
  ci/bundle.json ships the two new files; swagger fragment and engagement
  manifest regenerated; README lists DT.

Server 627/627 (16 new in test/dangerousTreasures.test.js) and every check;
client 92/92, build and externals. Booted against the pinned core: 45
triggers, 13 actions, 11 budgets, 21 option sources; 89 routes unchanged.

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

server/sidecarClient.js

@@ -435,6 +435,14 @@ const worldPlace = (server, body) => request(server, '/world/place', { method: '
  */
 const worldCall = (server, body) => request(server, '/world/call', { method: 'POST', body })
 
+/**
+ * Open one Dangerous Treasures event for a run's step (protocol 14, §20.8):
+ * `{ key, level }`. `data.kind` is `dt.opened` (with `x`, `z`, `level`, and
+ * `repeat: true` for a key the plugin has seen) or `dt.error` with a reason,
+ * `dt-not-ready` among them (D365). DT despawns its own chest: there is no revert.
+ */
+const dtStart = (server, body) => request(server, '/dt/start', { method: 'POST', body })
+
 /**
  * Give back what a run owns: named ids, else everything under a key, else the
  * whole run. `data` lists `removed`, `gone` (already not there — a success)
@@ -572,6 +580,7 @@ module.exports = {
   worldZone,
   worldPlace,
   worldCall,
+  dtStart,
   worldRevert,
   tallyOpen,
   tallySnapshot,