feat: add automation condition to filter private notes (#12102)

## Summary

Adds a new automation condition to filter private notes.

This allows automation rules to explicitly include or exclude private
notes instead of relying on implicit behavior.

Fixes: #11208 

## Preview



https://github.com/user-attachments/assets/c40f6910-7bbf-4e59-aae5-ad408602927a

app/javascript/dashboard/helper/automationHelper.js

@@ -150,6 +150,7 @@ export const getConditionOptions = ({
     conversation_language: languages,
     country_code: countries,
     message_type: messageTypeOptions,
+    private_note: booleanFilterOptions,
     priority: priorityOptions,
     labels: generateConditionOptions(labels, 'title'),
   };

app/javascript/dashboard/helper/specs/automationHelper.spec.js

@@ -178,6 +178,21 @@ describe('getConditionOptions', () => {
       })
     ).toEqual(testOptions);
   });
+
+  it('returns boolean options for private_note', () => {
+    const booleanOptions = [
+      { id: true, name: 'True' },
+      { id: false, name: 'False' },
+    ];
+
+    expect(
+      helpers.getConditionOptions({
+        booleanFilterOptions: booleanOptions,
+        customAttributes,
+        type: 'private_note',
+      })
+    ).toEqual(booleanOptions);
+  });
 });
 
 describe('getFileName', () => {