Remove in-app sponsor

app/src/main/java/io/nekohasekai/sfa/ui/MainActivity.kt

@@ -81,8 +81,6 @@ class MainActivity : AbstractActivity(), ServiceConnection.Callback {
         startIntegration()
 
         onNewIntent(intent)
-
-        Vendor.initializeBillingClient(this)
     }
 
     override fun onNewIntent(intent: Intent) {

app/src/main/java/io/nekohasekai/sfa/ui/main/SettingsFragment.kt

@@ -104,9 +104,7 @@ class SettingsFragment : Fragment() {
             startActivity(Intent(requireContext(), DebugActivity::class.java))
         }
         binding.startSponserButton.setOnClickListener {
-            Vendor.startSponsor(requireActivity()) {
-                activity.launchCustomTab("https://sekai.icu/sponsor/")
-            }
+            activity.launchCustomTab("https://sekai.icu/sponsors/")
         }
         lifecycleScope.launch(Dispatchers.IO) {
             reloadSettings()