feat(weeztix): auto company from OAuth, remove company UI

Store company_guid after OAuth via profile API; drop company select and
companies endpoint. Coupons AJAX uses stored company only. Form request
no longer accepts company fields from the browser.

Made-with: Cursor

app/Http/Controllers/Admin/WeeztixOAuthController.php

@@ -100,6 +100,10 @@ class WeeztixOAuthController extends Controller
         try {
             $service = new WeeztixService($config);
             $service->exchangeAuthorizationCode($request->string('code')->toString());
+            $config = $config->fresh();
+            if ($config !== null) {
+                (new WeeztixService($config))->ensureCompanyStoredFromWeeztix();
+            }
         } catch (RuntimeException $e) {
             Log::error('Weeztix OAuth callback failed', [
                 'page_id' => $page->id,