P1-P3 admin cleanup: rank guard, SSRF guard, count caching, dead code removal, pagination rewrite

- P1: new src/lib/admin/rank-guard.ts with tryGuardRank/guardRank + RankGuardTarget/Result; extracted from users.ts; applied to admin-bans (create/lift + rank redirect) and admin-badges (caps + rank guard + error surfacing); import-url-safety.ts SSRF guard wired into clone save+icon fetch; logAudit await in help-tickets; antiddos mutations SETTINGS_EDIT; markAllAlertsRead NOTIFICATIONS_EDIT; rankError/saveError in all 25 message files; tests rew/new for bans/badges/rank-guard/import-url-safety

- P2: ticket-inbox merged pagination reworked to single UNION ALL SQL with LIMIT/OFFSET (avoids O(offset) materialization); getCachedAdminCount with cacheFiltered option applied to devops/errors/photos/items/guilds/help-tickets/moderation pages; admin-theme catches→?error=1+banner+25 locales; logger in silent catches (rare-values/writeable-boxes); catalog-items-loader CAST→plain equality; count caching helper extended with opt-in cacheFiltered

- P3: removed dead modules is-staff/notice/recent-furni-resync/log-filters plus load-user-sanctions/user-sanction-timeline; removed orphaned CATALOG_PAGE_COLUMNS re-export; removed getFurniIconUrl from studio-furni-icons

Build: lint 0, typecheck 0, 3480 tests pass, i18n:check exit 0, colors exit 0. Circular chunk warning (9452/10535/66463) is webpack code-splitting artifact; build succeeds.

src/lib/admin-operations-contract.test.ts

@@ -73,6 +73,7 @@ const ACTION_GATES: Array<[string, string]> = [
 	["admin-ads.ts", "PERMS.PAGES_EDIT"],
 	["admin-vouchers.ts", "PERMS.SHOP_EDIT"],
 	["admin-alerts.ts", "PERMS.NOTIFICATIONS_EDIT"],
+	["admin-antiddos.ts", "PERMS.SETTINGS_EDIT"],
 	["commandocentrum.ts", "PERMS.RCON_EXECUTE"],
 	["translations.ts", "PERMS.SETTINGS_EDIT"],
 	["tickets.ts", "PERMS.TICKETS_EDIT"],