exclude compose activity from recents (#4521)

closes #4517

app/src/main/AndroidManifest.xml

@@ -99,9 +99,13 @@
                 android:value="androidx.sharetarget.ChooserTargetServiceCompat" />
 
         </activity>
+        <!-- When content is shared to Tusky ComposeActivity can be the only active activity,
+             so it must be excluded from recents or the sharing process can be restarted from recents
+             which would be very unexpected -->
         <activity
             android:name=".components.compose.ComposeActivity"
             android:theme="@style/TuskyDialogActivityTheme"
+            android:excludeFromRecents="true"
             android:windowSoftInputMode="stateVisible|adjustResize" />
         <activity
             android:name=".components.viewthread.ViewThreadActivity"