Fixed: drain session scroll counter on attach so viewport-hold never consumes stale background-streamed deltas

The emulator's scroll counter keeps growing while a session is not being viewed
(onTextChanged() skips the screen update - and clearScrollCounter() - when the
changed session is not current or the activity is not visible). attachSession()
reset the view state but left the counter intact: the first screen update after
attaching would hand the whole stale delta to the viewport-hold logic, which
treats it as "rows appended just now" and pins the view thousands of lines deep
into the scrollback, making scrolling appear dead in that session.

Discard the counter on attach - the user starts at the live bottom.

versionCode 1024 / versionName 0.119.0-titan2.2

app/build.gradle

@@ -43,8 +43,8 @@ android {
     defaultConfig {
         minSdkVersion project.properties.minSdkVersion.toInteger()
         targetSdkVersion project.properties.targetSdkVersion.toInteger()
-        versionCode 1023
-        versionName "0.119.0-titan2.1"
+        versionCode 1024
+        versionName "0.119.0-titan2.2"
 
         if (appVersionName) versionName = appVersionName
         validateVersionName(versionName)