✨ Allow selecting data sources

Right now all data sources get pumped into GPT
```[tasklist]
### Tasks
- [ ] In the UI add some checkboxes (or something better) to allow users to enable/disable data sources by default
- [ ] Everything on by default
- [ ] API endpoint shoud support this if #22 is done
```



e.g. 
- [x] emails
- [x] appointments
- [ ] teams calls
