feat: add Selenium Settings page to configure paymentGroupId per office

Adds a new Settings → Advanced → Selenium Settings page where the office
name (paymentGroupId) used in United/DentalHub portal dropdowns can be
configured without touching code. Previously hardcoded as "Summit Dental
Care"; now injected from DB into the three United workers at job dispatch.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/Backend/src/routes/insuranceStatusUnitedDHPreAuth.ts

@@ -3,6 +3,7 @@ import { storage } from "../storage";
 import { enqueueSeleniumJob } from "../queue/jobRunner";
 import { forwardOtpToSeleniumUnitedDHPreAuthAgent } from "../services/seleniumUnitedDHPreAuthClient";
 import { io } from "../socket";
+import { prisma as db } from "@repo/db/client";
 
 const router = Router();
 
@@ -40,11 +41,14 @@ router.post("/uniteddh-preauth", async (req: Request, res: Response): Promise<an
       });
     }
 
+    const seleniumSettings = await db.seleniumSettings.findUnique({ where: { userId: req.user.id } });
+
     const enrichedPayload = {
       claim: {
         ...claimData,
         uniteddhUsername: credentials.username,
         uniteddhPassword: credentials.password,
+        paymentGroupId: seleniumSettings?.paymentGroupId ?? "",
       },
     };