Claiming namespace `sumi-lang`

### Namespace

sumi-lang

### Ownership

- [x] The namespace is not currently owned on Open VSX (verify 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

### VS Code Publisher with Repo

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

### VS Code Publisher without Repo

- [ ] The namespace is also a publisher account on the VS Code Marketplace and does not have published extensions or has published extensions with no GitHub repos.

### Not a VS Code Marketplace Publisher

- [ ] The namespace is not a publisher account on the VS Code Marketplace

### All Other Cases

- [ ] You are unable to provide the inputs required in the three options above. This option will take the longest to process.

### Claim evidence

Commit URL: https://github.com/sumi-lang/sumi/commit/d6d5e42936eac626012f9b00f6ac0af359cbcb0b

Start by verifying the sumi-lang namespace on open-vsx.org and the publisher at marketplace.visualstudio.com/publishers/sumi-lang. Inspect the linked sumi-lang/sumi commit and its package.json repository entry for the required evidence. Done means the ownership request is verified and the namespace claim can be processed.

Written by the indexing model from the issue text.