feat(core): show ai-island and navigate to chat page if not available in sidebar (#13085)

close AI-318, AI-317

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

* **New Features**
* Updated the AI chat button label to "AFFiNE Intelligence" and changed
its icon for improved clarity.
* Enhanced the AI chat button's placement in the sidebar for better
accessibility.
* Improved the AI chat button’s visibility and interaction logic based
on current view and sidebar state.
* **Style**
* Adjusted button styles to disable interaction when hidden, enhancing
user experience.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/frontend/core/src/modules/workbench/view/route-container.css.ts

@@ -57,6 +57,8 @@ export const rightSidebarButton = style({
       opacity: 0,
       maxWidth: 0,
       marginLeft: 0,
+      // prevent click event from being triggered
+      pointerEvents: 'none',
     },
   },
 });