feat(GRO-1173): apply buffer rules UI changes to extracted groombook/web repo

This commit ports the GRO-1173 admin UI changes from the app monorepo
into the extracted groombook/web repo, using the correct source paths
(src/ instead of apps/web/src/):

- New BufferRulesSection component (full CRUD UI for /api/buffer-rules)
- Default Buffer (minutes) field added to service create/edit form
- Size Category and Coat Type dropdowns added to PetForm (portal)
- @groombook/types Service interface extended with defaultBufferMinutes
- BufferRulesSection embedded in Settings page

The PetForm already had coatType — this commit adds petSizeCategory
and renders both fields with proper dropdown selectors.

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

src/pages/Settings.tsx

@@ -1,5 +1,6 @@
 import { useState, useEffect, useRef } from "react";
 import { useBranding } from "../BrandingContext.js";
+import { BufferRulesSection } from "../components/BufferRules.js";
 
 interface AuthProviderConfig {
   id: number;
@@ -533,6 +534,10 @@ issuerUrl: authForm.issuerUrl,
         {saving ? "Saving..." : "Save Changes"}
       </button>
 
+      {/* Buffer Rules Section */}
+      <hr style={{ margin: "2rem 0", border: "none", borderTop: "1px solid #e5e7eb" }} />
+      <BufferRulesSection />
+
       {/* Auth Provider Section — super users only */}
       {currentUser?.isSuperUser && (
         <>