[TSP] Support the WebVH DID kind

This is needed to meet the Second stage TSP Milestone.

Currently Robrix only supports the basic "Web" DID type, which does not come with any verifiable history guarantees.

Implementation Notes

• The CreateDidModal already offers a radio button to select which DID type. Currently, WebVH is disabled, so we'd need to enable that.
• SDK-level support for WebVH used to be gated behind a webvh feature, but now it is apparently included under the resolve feature, which we already enable, so we should just be able to use it.
• There is a create_webvh() function here that we could likely use.
• For republishing a DID, we'll also need to support determining if an existing DID is Web or WebVH, and then republishing the correct version of it, along with whatever other DID "documents" are required when re-publishing a WebVH DID>

References

• Here is the TSP SDK CLI example's code for creating a WebVH DID: https://github.com/openwallet-foundation-labs/tsp/blob/c68c49c94ac1f74f559d961c92c99a3a4f10b219/examples/src/cli.rs#L421
• There isn't much documentation on WebVH, but they are briefly mentioned in the TSP intro docs here: https://docs.teaspoon.world/cli/base.html?highlight=webvh#supported-did-types

Start at the CreateDidModal entry point and inspect how the existing Web DID creation and republishing paths use the TSP SDK. Read the SDK create_webvh() function and the linked CLI example first, then determine how existing DID kinds and required documents are handled. Done means WebVH can be selected, created, identified, and republished correctly alongside Web DIDs.