Claiming namespace [rive]

### Namespace

rive

### Ownership

- [x] The namespace is not currently owned on Open VSX (verified by a search on [open-vsx.org](https://open-vsx.org))

### Account Age

- [x] The GitHub ID making this request has at least 12 months of public history

### Option 1: VS Code Publisher with Repo

- [x] The namespace is also a publisher account on the VS Code Marketplace (https://marketplace.visualstudio.com/publishers/rive) and has an extension published there with a repo specified in its package.json file.

- [x] The extension repo, public or private, is owned by the GitHub ID making this request (same org)

### Claim evidence

We are the publisher `rive` on the VS Code Marketplace with the published extension [rive.rive-vscode](https://marketplace.visualstudio.com/items?itemName=rive.rive-vscode), whose package.json `repository` field points at https://github.com/rive-app/rive-vscode, owned by the rive-app org of which I am a member. `ovsx create-namespace rive` is currently rejected by the similarity check against the existing "River" namespace, so we are requesting the namespace here. We also own the rive.app domain and are happy to add a DNS TXT record referencing this issue if further validation helps.

Review the namespace checklist, the linked VS Code Marketplace publisher, and the extension's package.json repository field. Check the ownership and account-age evidence, then verify whether the similarity check or DNS TXT validation needs follow-up; done means the rive namespace claim is accepted or a clear validation response is posted.

Written by the indexing model from the issue text.