Windows installer requires execution policy

When trying the installer script for uv on windows 11 in powershell, i get an error:

```
PS > powershell -c "irm https://astral.sh/uv/install.ps1 | iex"
Error: PowerShell requires an execution policy in [Unrestricted, RemoteSigned, ByPass] to run uv. For example, to set the execution policy to 'RemoteSigned' please run:

Set-ExecutionPolicy RemoteSigned -scope CurrentUser

```

Running that command doesn't help instead i need to

```
powershell -ExecutionPolicy Bypass -c "irm https://astral.sh/uv/install.ps1 | iex"
```

Start by reproducing the Windows 11 PowerShell command against https://astral.sh/uv/install.ps1, then inspect the installer script's execution-policy check and its suggested Set-ExecutionPolicy command. Done means the reported command works as documented, or the installer gives accurate instructions for the required policy.

Written by the indexing model from the issue text.