Make draft schema URL point to actual location

(Issue drafted by Claude Code, finalized by me)

Context

Follow-up from PR #803 (https://github.com/modelcontextprotocol/registry/pull/803#issuecomment-3607768736)

In PR #803, the schema URL label was updated to clarify that the in-repo schema is a draft version, using the URL:
https://static.modelcontextprotocol.io/schemas/draft/server.schema.json

Problem

This draft schema URL does not actually exist, which could confuse users who try to access it directly. While the label helps distinguish the in-repo version from finalized versions in static hosting, the non-existent URL is misleading.

Proposed Solution

Update the reference to point more directly at the current draft location (e.g., a raw GitHub URL to the schema in the repo)

Priority

Low priority - the main goal of distinguishing draft vs released schemas was achieved in #803. This is a polish improvement.