remove the need for application package name in the androidManifest for the external signer

app/src/main/AndroidManifest.xml

@@ -3,8 +3,11 @@
     xmlns:tools="http://schemas.android.com/tools">
     <queries>
         <package android:name="org.torproject.android"/>
-        <package android:name="com.greenart7c3.nostrsigner"/>
-        <package android:name="com.greenart7c3.nostrsigner.debug"/>
+        <intent>
+            <action android:name="android.intent.action.VIEW" />
+            <category android:name="android.intent.category.BROWSABLE" />
+            <data android:scheme="nostrsigner" />
+        </intent>
     </queries>
 
     <!-- Doesn't require a camera -->

app/src/main/java/com/vitorpamplona/amethyst/service/PackageUtils.kt

@@ -21,6 +21,8 @@
 package com.vitorpamplona.amethyst.service
 
 import android.content.Context
+import android.content.Intent
+import android.net.Uri
 
 object PackageUtils {
     private fun isPackageInstalled(
@@ -36,7 +38,13 @@ object PackageUtils {
         return isPackageInstalled(context, "org.torproject.android")
     }
 
-    fun isAmberInstalled(context: Context): Boolean {
-        return isPackageInstalled(context, "com.greenart7c3.nostrsigner")
+    fun isExternalSignerInstalled(context: Context): Boolean {
+        val intent =
+            Intent().apply {
+                action = Intent.ACTION_VIEW
+                data = Uri.parse("nostrsigner:")
+            }
+        val infos = context.packageManager.queryIntentActivities(intent, 0)
+        return infos.size > 0
     }
 }

app/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedOff/LoginScreen.kt

@@ -458,7 +458,7 @@ fun LoginPage(
             }
         }
 
-        if (PackageUtils.isAmberInstalled(context)) {
+        if (PackageUtils.isExternalSignerInstalled(context)) {
             Box(modifier = Modifier.padding(40.dp, 20.dp, 40.dp, 0.dp)) {
                 Button(
                     enabled = acceptedTerms.value,