skills="all" does not add "Skill" to tools

### Claude can sometimes not use skills with `skills="all"` and defined `tools`

All examples in the [documentation](https://code.claude.com/docs/en/agent-sdk/skills) set `skills="all"` and that's it, seems to work.
I have spend a whole lot of time debugging why my skills suddenly don't work anymore:
Apparently, you still need to add `"Skill"` to `tools` if you define tools explicitly.
This only happened while running my agent in a kubernetes job, locally everything worked fine. I have no idea why, probably something in my global settings that gets read locally but is not available in the cloud.

```python
ClaudeAgentOptions(
# ... other stuff
setting_sources=["project"],
tools=["WebSearch", "WebFetch", "Read"], # <-- I had to add "Skill" here for it to work
allowed_tools=["WebSearch", "WebFetch", "Read"],
skills="all",
)
```

This is especially confusing since the doc string of `allowed_tools` reads to "configure everything", which does not seem to be the case.