Add model selection support in custom token mode, Please!!!

[qybgh]

1. Suggestion: Add model selection support in custom token mode
   Description: In custom token mode, it would be very useful to allow users to specify a default model. This feature is critical for certain use cases where different models (e.g., GPT-4 or GPT-3.5) are required for specific tasks.
   Recommendation: Add a feature in the settings to let users select a default model when using their own API tokens.

2. Design issue with the pop-up behavior after selecting text
   Phenomenon: After selecting text and clicking the pop-up bubble, the pop-up window closes when clicking outside of it. This behavior does not meet user expectations.
   Suggestions for improvement: Align the behavior of the pop-up triggered by text selection with that of the shortcut-triggered pop-up, ensuring consistency.
   Provide an option for users to customize the behavior (e.g., whether the pop-up should close automatically when clicking outside).

3. Issue with shortcut keys not working occasionally
   Phenomenon: The shortcut keys sometimes fail to wake up the application, and the cause is unclear.