chore(lint): remove all 34 dead-code warnings (verified site by site)

unused-vars (25): leftover imports/types across pages, routes and services;
write-only sickHours accumulator; unused holidayCount pair; test helpers
authPatch/authDelete; TOut dropped from ApiMutationOptions (the hook keeps
its own generic — no call-site changes); requireAuth no longer importable
in customers/warehouse routes (matches the no-bare-auth-reads convention).

useless-assignment (5): initializers proven overwritten on every path
(systemQty x2, hours, writtenSize -> let x: number) and the seed's dead
adminUser reassignment (create kept, assignment dropped).

useless-escape (4): [eE+\-] -> [eE+-] and [\/...] -> [/...] — identical
semantics.

Behavior-neutral; lint 102 -> 68 warnings (0 errors), suite 641 green.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/admin/pages/CompanySettings.tsx

@@ -3,10 +3,7 @@ import { useQuery, useQueryClient } from "@tanstack/react-query";
 import { useAlert } from "../context/AlertContext";
 import { useAuth } from "../context/AuthContext";
 import Forbidden from "../components/Forbidden";
-import {
-  companySettingsOptions,
-  type CompanySettingsData,
-} from "../lib/queries/settings";
+import { companySettingsOptions } from "../lib/queries/settings";
 import { bankAccountsOptions, type BankAccount } from "../lib/queries/common";
 import Box from "@mui/material/Box";
 import Typography from "@mui/material/Typography";
@@ -23,7 +20,6 @@ import {
   TextField,
   Select,
   CheckboxField,
-  StatusChip,
   FileUpload,
   LoadingState,
   type DataColumn,