Site-wide API tokens

### Describe the problem

Hi

is it be possible to have a dedicated monitoring token to scrape Weblate's metrics?
I can either use my personal user token or a per project token (https://docs.weblate.org/fr/weblate-2026.6.1/admin/access.html#project-api)

I decided to create a fake per project token with a limited access until I find something better.

Here is the configuration I'm using for prometheus
```
scrape_configs:
- job_name: fedoraweblate
metrics_path: "/api/metrics/"
scheme: "https"
params:
format: ['openmetrics']
bearer_token: THE_TOKEN
static_configs:
- targets: ['translate.fedoraproject.org']
```

### Solution brainstorm

maybe admin screen should ability to create API users the same way we have for project?

### Describe alternatives you have considered

create fake users, use per project API user, use my own user token

### Screenshots

_No response_

### Additional context

_No response_