feat(rust): slash commands and the next wipe, server half (phase 16)

Five read-only commands registered with api.registerSlashCommands:
/status, /wipe, /top, /online and /clan (D126). Every refusal is private,
and any answer narrower than public (online names, a clan roster) goes
to the caller alone (D127). No command asks a sidecar.

The next wipe (D128, D130): six nullable columns on rust_servers, a pure
nextWipe(row, now) with the zone arithmetic through Intl, computed on
every read. The public server shape gains nextWipe; the admin shape
gains the stored schedule; PUT /admin/rust/servers/:id takes the six
fields and writes them only when wipeRule is present.

server/commands joins ci/bundle.json, which checkBundle caught.

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

server/db/schema.sql

@@ -900,3 +900,30 @@ CREATE TABLE IF NOT EXISTS rust_map_overrides (
   CONSTRAINT fk_rust_map_overrides_user
     FOREIGN KEY (updated_by) REFERENCES users (id) ON DELETE SET NULL
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;
+
+-- ── The next wipe (phase 16, D128 · D130) ─────────────────────────────────
+--
+-- What an operator says about a server's wipe calendar: a rule, and an optional
+-- one-off date. The next wipe itself is NOT stored — it is computed from these on
+-- every read (`model/servers/nextWipe.js`), so nothing rolls it forward after a
+-- wipe and nothing can go stale.
+--
+--   wipe_rule     `none` · `forced` · `weekly` · `biweekly`. `none` forecasts
+--                 nothing; every other rule includes Facepunch's forced wipe.
+--   wipe_day      0 (Sunday) … 6, for weekly and biweekly
+--   wipe_time     `HH:MM`, 24-hour, on the wall clock of…
+--   wipe_tz       an IANA zone. The server's own, because a wipe announced as
+--                 "Thursday 14:00" means 14:00 where the operator is, summer or
+--                 winter; a UTC time would drift by an hour twice a year.
+--   wipe_anchor   one wipe on a biweekly rule, which says WHICH weeks
+--   wipe_once_at  a one-off wipe, UTC. While it is in the future it IS the next
+--                 wipe; once passed it is ignored rather than cleared.
+--
+-- A word this build does not recognise reads as `none`: a forecast nobody made
+-- must not appear.
+ALTER TABLE rust_servers ADD COLUMN IF NOT EXISTS wipe_rule VARCHAR(16) NOT NULL DEFAULT 'none';
+ALTER TABLE rust_servers ADD COLUMN IF NOT EXISTS wipe_day TINYINT NULL;
+ALTER TABLE rust_servers ADD COLUMN IF NOT EXISTS wipe_time CHAR(5) NULL;
+ALTER TABLE rust_servers ADD COLUMN IF NOT EXISTS wipe_tz VARCHAR(64) NULL;
+ALTER TABLE rust_servers ADD COLUMN IF NOT EXISTS wipe_anchor DATE NULL;
+ALTER TABLE rust_servers ADD COLUMN IF NOT EXISTS wipe_once_at DATETIME NULL;