fix: prevent repeated 'Process Completed' messages after LLM translation

Root cause: setInterval with async callbacks does not prevent overlapping
execution. pywebview's message queue backs up during heavy LLM token
streaming (dense stdout from local LLM). When the process exits and load
drops, all backed-up get_process_status() calls resolve simultaneously —
each sees status='completed' and each calls ErrorHandler.showSuccess,
printing the success message many times.

Fix: add a guard immediately after each `await pywebview.api.*` call that
checks `AppState.statusPollInterval` (or logPollInterval). The first
callback to handle completion calls stopStatusMonitoring() which sets
the ref to null. All subsequent in-flight callbacks see null and return
early, executing the completion handler exactly once.

Applied to both startStatusMonitoring (500ms) and startLogPolling (100ms).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: meizhong986

whisperjav/webview_gui/assets/app.js

@@ -949,6 +949,9 @@ const ProcessManager = {
             try {
                 const logs = await pywebview.api.get_logs();
 
+                // Guard against overlapping async callbacks (same race as status monitor)
+                if (!AppState.logPollInterval) return;
+
                 if (logs && logs.length > 0) {
                     logs.forEach(line => {
                         // Remove trailing newline if present
@@ -978,6 +981,14 @@ const ProcessManager = {
             try {
                 const status = await pywebview.api.get_process_status();
 
+                // Guard: another concurrent callback may have already handled completion
+                // and called stopStatusMonitoring() while this one was awaiting.
+                // setInterval with async callbacks does not prevent overlap — multiple
+                // in-flight callbacks can all see status='completed' when the pywebview
+                // message queue drains after heavy LLM streaming. Only the first one
+                // should act; the rest must exit here.
+                if (!AppState.statusPollInterval) return;
+
                 // Update status label
                 ProgressManager.setStatus(this.formatStatus(status.status));