fix(GRO-1489): resolve 7 lint errors blocking dev CI

- Remove unused gte, lt, ne imports from cascade.ts
- Rename originalEndTime → _originalEndTime in detectAndCascadeOverrun params
- Rename originalStartTime/newStartTime → _originalStartTime/_newStartTime in isOverrun params
- Remove unused petCoatType assignment in book.ts availability route
- Align x-large → xlarge in Book.tsx size option value and duration display

Unblocks: GRO-1481 promotion (PR #428)

Co-Authored-By: Paperclip <noreply@paperclip.ing>

apps/api/src/routes/book.ts

@@ -44,7 +44,6 @@ bookRouter.get("/availability", async (c) => {
   const serviceId = c.req.query("serviceId");
   const dateStr = c.req.query("date");
   const petSizeCategory = c.req.query("petSizeCategory") ?? undefined;
-  const petCoatType = c.req.query("petCoatType") ?? undefined;
 
   if (!serviceId || !dateStr) {
     return c.json({ error: "serviceId and date are required" }, 400);