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/WarehouseIssueForm.tsx

@@ -65,7 +65,7 @@ interface BatchesResponse {
 }
 
 function parseDecimal(raw: string): number {
-  const cleaned = raw.replace(/[eE+\-]/g, "");
+  const cleaned = raw.replace(/[eE+-]/g, "");
   const n = Number(cleaned);
   return Number.isFinite(n) ? n : 0;
 }