feat: cost warning

**Is your feature request related to a problem? Please describe.**
Currently there is a scenario when AI CLI can make expensive API call without user confirmation. This happens when user use `--file` option and asks a query in CLI params. In such case, even when the price threshold is exceeded and user gets a warning, he is not able to prevent this API call.

**Describe the solution you'd like**
In case file context is used, and user exceeds warning threshold for context and, and there is a query in CLI params: then CLI should ask user to confirm if it should make the API call before making it.

```shell-session
# ai -i --file file.md Some question
Using the provided file will increase conversation costs by $1.1193 per message.
Do you want to continue? [y/N]:
```

**Describe alternatives you've considered**
Warning as is, but there is a risk of making expensive API can which user would not want if he knew the costs.

**Additional context**
We should use current cost calculation features.
In rare case cost is not available, we should refer to token count.