fix(gro-48): use staffRow?.role for consistency with clients.ts/pets.ts

QAP-125 noted appointments.ts uses staffRow.role (unsafe) while
clients.ts/pets.ts use staffRow?.role (safe). This inconsistency
can cause runtime errors when staff context is missing. Fixed by
using the safe optional-chain form consistently in both GET handlers.

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

apps/api/src/routes/appointments.ts

@@ -73,7 +73,7 @@ appointmentsRouter.get("/", async (c) => {
   const to = c.req.query("to");
   const staffId = c.req.query("staffId");
   const staffRow = c.get("staff");
-  const isGroomer = staffRow.role === "groomer";
+  const isGroomer = staffRow?.role === "groomer";
 
   const conditions = [];
   if (from) conditions.push(gte(appointments.startTime, new Date(from)));
@@ -108,7 +108,7 @@ appointmentsRouter.get("/", async (c) => {
 appointmentsRouter.get("/:id", async (c) => {
   const db = getDb();
   const staffRow = c.get("staff");
-  const isGroomer = staffRow.role === "groomer";
+  const isGroomer = staffRow?.role === "groomer";
   const [row] = await db
     .select()
     .from(appointments)