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/__tests__/plan.test.ts

@@ -1090,26 +1090,6 @@ async function authPost(path: string, token: string, body: unknown) {
   });
 }
 
-async function authPatch(path: string, token: string, body: unknown) {
-  return app.inject({
-    method: "PATCH",
-    url: path,
-    headers: {
-      Authorization: `Bearer ${token}`,
-      "Content-Type": "application/json",
-    },
-    payload: body as object,
-  });
-}
-
-async function authDelete(path: string, token: string) {
-  return app.inject({
-    method: "DELETE",
-    url: path,
-    headers: { Authorization: `Bearer ${token}` },
-  });
-}
-
 beforeAll(async () => {
   app = await buildApp();