fix(ai-chat): abort in-flight Claude query on destroySession

destroySession was nulling currentAbortController without calling
.abort() on it first, so clicking "+ New" while the AI was streaming
left the Claude query churning in the background. Now mirrors the
resumeSession path: abort first, then null. Adds i18n strings for the
new "AI is working" confirmation dialogs surfaced by the chat panel
when New / history-resume interrupt a streaming run.

Author: abose

src-node/claude-code-agent.js

@@ -673,8 +673,11 @@ exports.resumeSession = async function (params) {
  * Destroy the current session (clear session ID).
  */
 exports.destroySession = async function () {
+    if (currentAbortController) {
+        currentAbortController.abort();
+        currentAbortController = null;
+    }
     currentSessionId = null;
-    currentAbortController = null;
     _queuedClarification = null;
     return { success: true };
 };

src/nls/root/strings.js

@@ -2368,6 +2368,10 @@ define({
     "AI_CHAT_HISTORY_DELETE_CONFIRM": "Delete this session?",
     "AI_CHAT_SWITCH_PROJECT_TITLE": "AI is working",
     "AI_CHAT_SWITCH_PROJECT_MSG": "AI is currently working on a task. Switching projects will stop it. Continue?",
+    "AI_CHAT_NEW_WHILE_STREAMING_TITLE": "AI is working",
+    "AI_CHAT_NEW_WHILE_STREAMING_MSG": "AI is currently working on a task. Starting a new conversation will stop it. Continue?",
+    "AI_CHAT_RESUME_WHILE_STREAMING_TITLE": "AI is working",
+    "AI_CHAT_RESUME_WHILE_STREAMING_MSG": "AI is currently working on a task. Switching to a previous conversation will stop it. Continue?",
     "AI_CHAT_SETTINGS_TITLE": "Claude Code Settings",
     "AI_SETTINGS_API_KEY": "API Key",
     "AI_SETTINGS_BASE_URL": "Base URL",