feat(rust): Guarded Crate — feed, map, Warden, Place a guarded crate (PLAN_REDESIGNS §14.3.5)

Stage 6 of the §14.3 integration plan, on protocol 14. Spec: docs
rust-link/PROTOCOL.md §20.9.

- gc.started and gc.ended public, gc.failed staff's; guardedCrate.js reads
  each row per viewer (the clearer's name for the presence audience, Steam id,
  position and key for staff, `won` for everyone).
- Triggers rust.gc.started and rust.gc.ended (a crate a player cleared only).
- The step rust.gc.place: an event from rust.options.gc_events and a world
  call's location; refused at verify for Guarded Crate absent, NpcSpawn missing
  (D364), console unavailable, or an unknown event. Kept (D373); the run log's
  success line says so (D380). Budget rust.gc.crates.
- Warden (D375): guarded_won, title category guardedwon, Crates cleared column.
- Map marker, server settings line, swagger, engagement manifest, bundle, README.

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

server/sidecarClient.js

@@ -443,6 +443,15 @@ const worldCall = (server, body) => request(server, '/world/call', { method: 'PO
  */
 const dtStart = (server, body) => request(server, '/dt/start', { method: 'POST', body })
 
+/**
+ * Place one guarded crate for a run's step (protocol 14, §20.9): `{ key, event }`
+ * and a location as a world call takes one (`monument` and offsets, or `x` and
+ * `z`). `data.kind` is `gc.placed` (with `event`, `x`, `z`, and `repeat: true`
+ * for a key the plugin has seen) or `gc.error` with a reason, `npcspawn-missing`
+ * among them (D364). The crate is kept when the run ends (D373): there is no revert.
+ */
+const gcPlace = (server, body) => request(server, '/gc/place', { 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)
@@ -581,6 +590,7 @@ module.exports = {
   worldPlace,
   worldCall,
   dtStart,
+  gcPlace,
   worldRevert,
   tallyOpen,
   tallySnapshot,