Premium mode now works in every project

Picking Premium mode in the AI chat sometimes did nothing in a freshly opened project - the switch quietly snapped back to Economy. That's fixed: your mode choice now sticks in every project, even before you've sent your first message.

Improvements

• Premium mode is selectable everywhere - the choice is saved the moment you make it, in any project
• Set your default mode - choose whether new chats start in Economy or Premium from Preferences > AI Model > Default Mode, and it applies across all your projects