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## Summary by CodeRabbit
* **New Features**
* Added support for the "AI Playground" experimental feature, including
new settings and localization entries.
* **Refactor**
* Renamed configuration and service references from "Model Switch" to
"Playground" across the AI chat and playground interfaces.
* Updated feature flag from "enable_ai_model_switch" to
"enable_ai_playground" for consistency.
* **Bug Fixes**
* The "Model" submenu in AI chat preferences is now always visible,
simplifying menu options.
* **Chores**
* Removed outdated Claude model options from the chat prompt.
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