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/db/schema.sql

@@ -1390,3 +1390,7 @@ ALTER TABLE rust_servers ADD COLUMN IF NOT EXISTS credit_rule VARCHAR(8) NOT NUL
 -- Dangerous Treasures (protocol 14, PLAN_REDESIGNS §14.3.4, D375): the treasure
 -- chests a player emptied, from the tally like the others (Treasure Hunter).
 ALTER TABLE rust_player_wipe_stats ADD COLUMN IF NOT EXISTS treasures_won INT UNSIGNED NOT NULL DEFAULT 0;
+
+-- Guarded Crate (protocol 14, PLAN_REDESIGNS §14.3.5, D375): the guarded crates
+-- a player cleared by killing the last guard, from the tally like the others (Warden).
+ALTER TABLE rust_player_wipe_stats ADD COLUMN IF NOT EXISTS guarded_won INT UNSIGNED NOT NULL DEFAULT 0;