fix: lock onTermuxSessionExited removal and use session snapshot for working-dir lookup to keep getTermuxSessionsListSnapshot consistent and avoid concurrent-modification races

Author: jatezzz

termux/termux-app/src/main/java/com/termux/app/TermuxActivity.java

@@ -469,7 +469,7 @@ public void onServiceConnected(ComponentName componentName, IBinder service) {
         } else {
 
             final Optional<TermuxSession> existingSession = workingDir == null ? Optional.empty() :
-                mTermuxService.getTermuxSessions().stream().filter(session -> Objects.equals(
+                mTermuxService.getTermuxSessionsListSnapshot().stream().filter(session -> Objects.equals(
                     session.getTerminalSession().getCwd(), workingDir)).findFirst();
 
             setupTermuxSessionOnServiceConnected(

termux/termux-app/src/main/java/com/termux/app/TermuxService.java

@@ -651,7 +651,7 @@ public synchronized int removeTermuxSession(TerminalSession sessionToRemove) {
 
     /** Callback received when a {@link TermuxSession} finishes. */
     @Override
-    public void onTermuxSessionExited(final TermuxSession termuxSession) {
+    public synchronized void onTermuxSessionExited(final TermuxSession termuxSession) {
         if (termuxSession != null) {
             ExecutionCommand executionCommand = termuxSession.getExecutionCommand();