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>

packages/db/shared/schemas/variants/index.ts

@@ -0,0 +1,8 @@
+/**
+ * Schema Variants Index
+ * Auto-generated - do not edit manually
+ */
+
+export * from './pure';
+export * from './input';
+export * from './result';