Fix: Add title field to LinearComment to prevent AttributeError

[codegen-sh]

Description

This PR fixes an error that occurs when handling Linear comment events. The error message is:

'LinearComment' object has no attribute 'title'

The issue happens when code tries to access event.data.title on a LinearComment object, but the LinearComment class doesn't have a title attribute.

Changes

• Added an optional title field with a default value of None to the LinearComment class
• Updated type hints to use more explicit Optional and Union types from the typing module

Testing

This change should prevent the AttributeError when handling Linear comment events while maintaining backward compatibility with existing code.

Fixes issue CG-17839