Re-adds support form Assistant response using a lighter weight
Streamdown component vs the more heavy `Message` component.
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## Summary by CodeRabbit
* **New Features**
* AI Assistant follow-up card after ticket submission for project-scoped
requests.
* In-chat support request preview panels showing submitted subject and
message.
* **Improvements**
* Smarter project selection when opening the support form via
route/context.
* Success screen: cleaner layout, project-name messaging, optional
finish action, and a "Join Discord" button.
* Category prompt text updated to "What issue are you having?"
* New success/feedback section for consistent layouts.
* **Tests**
* Added tests covering support prompt serialization/parsing and UI
previews.
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