The `Assign to collections` modal allows moving an individual vault item to a Client Organization from the Provider Portal.

### Steps To Reproduce

1. You'd need to have an individual Bitwarden account that's associated with an Organization and also with a Provider Portal.
2. Log into your individual Bitwarden account via the Bitwarden Web App.
3. Click on the ellipsis next to a vault item that's stored within your individual vault, and click on `Assign to collections`.

### Expected Result

Within the `Move to organization` field, you should be shown only organizations which you are a member of.

### Actual Result

Within the `Move to organization` field, you are shown organizations you're a member of and also Client Organization from your Provider Portal.

### Screenshots or Videos

Internal.

### Additional Context

The desktop client does not offer Client Organizations via its `Move to organization` function, and the `Owner` field within a vault item's `Edit` modal also does not offer Client Organizations.

### Operating System

Windows

### Operating System Version

11 Pro 24H2

### Web Browser

Firefox

### Browser Version

137.0.1

### Build Version

2025.3.1

### Issue Tracking Info

- [x] I understand that work is tracked outside of Github. A PR will be linked to this issue should one be opened to address it, but Bitwarden doesn't use fields like "assigned", "milestone", or "project" to track progress.

Reproduce the issue in the Bitwarden Web App using an individual account associated with an organization and Provider Portal, then inspect the Assign to collections modal and its Move to organization field. Compare the available organizations with the desktop client's behavior; done means Client Organizations no longer appear for individual vault items while member organizations remain available.

Written by the indexing model from the issue text.