feat(rust): zone presets, and the zone step's options, messages and dome (PLAN_REDESIGNS §3, D210)

Admin → Rust zone presets: named sets of ZoneManager flags and settings for
one server, several, or every server (D195), ticked in groups read from each
server's own ZoneManager list in its last hello (D211). A flag not on a
covered server is refused on save with the server named; two presets of one
name may not share a server.

rust.zone.open gains options (one line, NoBuild, radiation=10), enterMessage,
leaveMessage, delivery, dome and domeStack. The options field's dropdown is
rust.options.zone_presets, whose row VALUE is the preset's line, so picking
one copies it into the step (D210) and no published event changes when a
preset does. The line and the dome are checked against the server's hello
on save and in a dry run; bad-option and dome-unavailable are permanent.

Schema: rust_zone_presets, rust_zone_preset_servers. Swagger fragment and
routes.manifest regenerated against the pinned core f0e7d2a.

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

server/db/schema.sql

@@ -1163,3 +1163,41 @@ ALTER TABLE rust_servers ADD COLUMN IF NOT EXISTS perm_policy VARCHAR(16) NOT NU
 -- `split` (D190 gave a server its own copy of a shared group, and says so in
 -- case the change was meant for every server).
 ALTER TABLE rust_perm_drift ADD COLUMN IF NOT EXISTS direction VARCHAR(16) NOT NULL DEFAULT 'added';
+
+-- ── Zone presets (PLAN_REDESIGNS §3.1, D195, D210) ─────────────────────────
+--
+-- A set of ZoneManager flags and settings an admin saved under a name, for one
+-- server, several, or the whole fleet. None ship with the module: what an
+-- "arena" is differs by server. A zone step copies a preset's options into its
+-- own field when the preset is picked (D210), so editing a preset later leaves
+-- every published event as it was.
+--
+-- `flags` is a JSON array of names as ZoneManager spells them, `settings` a JSON
+-- object of the plugin's allowlisted settings. Both are TEXT, not JSON: MariaDB's
+-- JSON is an alias the driver hands back as a string either way.
+CREATE TABLE IF NOT EXISTS rust_zone_presets (
+  id           INT UNSIGNED  NOT NULL AUTO_INCREMENT PRIMARY KEY,
+  name         VARCHAR(64)   NOT NULL,
+  flags        TEXT          NOT NULL,
+  settings     TEXT          NOT NULL,
+  -- 1: every server, including servers added later. 0: exactly the servers
+  -- `rust_zone_preset_servers` names. The shape of a shared group (§1.4).
+  all_servers  TINYINT(1)    NOT NULL DEFAULT 0,
+  created_by   INT           NULL,
+  created_at   DATETIME      NOT NULL DEFAULT CURRENT_TIMESTAMP,
+  updated_at   DATETIME      NOT NULL DEFAULT CURRENT_TIMESTAMP,
+  -- Not unique: two servers may each have their own "Arena" (D189's rule for
+  -- groups). The model refuses two of one name on one server.
+  KEY idx_rust_zone_presets_name (name)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;
+
+CREATE TABLE IF NOT EXISTS rust_zone_preset_servers (
+  preset_id  INT UNSIGNED  NOT NULL,
+  server_id  VARCHAR(64)   NOT NULL,
+  PRIMARY KEY (preset_id, server_id),
+  KEY idx_rust_zone_preset_servers_server (server_id),
+  CONSTRAINT fk_rust_zone_preset_servers_preset
+    FOREIGN KEY (preset_id) REFERENCES rust_zone_presets (id) ON DELETE CASCADE,
+  CONSTRAINT fk_rust_zone_preset_servers_server
+    FOREIGN KEY (server_id) REFERENCES rust_servers (id) ON DELETE CASCADE
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;