fix(chat-client): fix bug where pair programmer mode option update was not stored properly (#1400)

`OnPromptInputOptionChange` event when the agentic mode button is toggled on and off, the mynahUI store was not updated properly to store the updated value. This resulted in "insert to cursor" option being disabled/hidden in a codeblock shown in an agentic mode OFF response.

Solution
With this change, on prompt option change event, the MynahUi store is now updated to preserve the latest value of "pair-programmer-mode" option. I verified the insert to cursor option now appears on toggle

Author: shruti0085

chat-client/src/client/mynahUi.ts

@@ -91,6 +91,18 @@ export const handlePromptInputChange = (mynahUi: MynahUI, tabId: string, options
 
     if (promptTypeValue != null) {
         mynahUi.addChatItem(tabId, promptTypeValue === 'true' ? pairProgrammingModeOn : pairProgrammingModeOff)
+        const options = [...(mynahUi.getTabData(tabId)?.getStore()?.promptInputOptions || [])]
+        const optionIndex = options.findIndex(opt => opt.id === 'pair-programmer-mode')
+
+        if (optionIndex >= 0) {
+            options[optionIndex].value = promptTypeValue
+        } else {
+            options.push({
+                id: 'pair-programmer-mode',
+                value: promptTypeValue,
+            } as any)
+        }
+        mynahUi.updateStore(tabId, { promptInputOptions: options as any })
     }
 }