Consider `/.wk/mcp-registry-auth` => `/.wk/mcp/registry-auth`

[jonathanhefner]

(Not really sure if this is a GA blocker, but wanted to raise attention, just in case.)

The MCP Registry currently uses /.well-known/mcp-registry-auth for DNS-based auth:

registry/docs/explanations/namespacing.md

Line 26 in 68213d2

- HTTP verification: File at `https://company.com/.well-known/mcp-registry-auth`

However, there is a desire to support /.well-known/mcp/server.json. For example, see modelcontextprotocol/modelcontextprotocol#1649.

So should we change /.well-known/mcp-registry-auth to /.well-known/mcp/registry-auth?

[scottschreckengaust]

Suggestion to update #850 and add another well-known path to IANA. There is an agent-card.json for A2A.