fix(spec): freeze 2026-07-28 release references

[squarepots]

Closes #2857.

What

Finish the 2026-07-28 draft-to-release cutover.

• pin 2026-07-28 to the released spec commit;
• use schema/2026-07-28 for the generated type anchor, schema twin, and example corpus;
• carry the final released SubscriptionsListenResultMetaObject and SubscriptionsListenResultResponse reference shapes into parity/conformance coverage;
• record each schema twin's source commit so freezing 2026 does not move the 2025 oracle;
• remove the nightly workflow that still refreshes released 2026 from schema/draft;
• update the lifecycle documentation for released and draft revisions.

Why

2026-07-28 is already released, but the current reference lifecycle still follows the draft schema. The nightly job updates only the generated anchor, while the repository requires the anchor and its derived oracles to stay synchronized.

That leaves a released revision with a moving authority and repeatedly recreates drift between the anchor, schema twin, and fixtures.

Validation

Validated on the fork PR:

• check:all;
• build:all and distribution type smoke test;
• Node 20/22/24 tests and e2e;
• Bun and Deno runtime tests;
• client and server conformance;
• examples build + e2e and guide examples.

[changeset-bot]

⚠️ No Changeset found

Latest commit: 9b24218

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets

When changesets are added to this PR, you'll see the packages that this PR includes changesets for and the associated semver types

Click here to learn what changesets are, and how to add one.

Click here if you're a maintainer who wants to add a changeset to this PR

[pkg-pr-new]

Open in StackBlitz

@modelcontextprotocol/client

npm i https://pkg.pr.new/@modelcontextprotocol/client@2858

@modelcontextprotocol/codemod

npm i https://pkg.pr.new/@modelcontextprotocol/codemod@2858

@modelcontextprotocol/core

npm i https://pkg.pr.new/@modelcontextprotocol/core@2858

@modelcontextprotocol/server

npm i https://pkg.pr.new/@modelcontextprotocol/server@2858

@modelcontextprotocol/server-legacy

npm i https://pkg.pr.new/@modelcontextprotocol/server-legacy@2858

@modelcontextprotocol/express

npm i https://pkg.pr.new/@modelcontextprotocol/express@2858

@modelcontextprotocol/fastify

npm i https://pkg.pr.new/@modelcontextprotocol/fastify@2858

@modelcontextprotocol/hono

npm i https://pkg.pr.new/@modelcontextprotocol/hono@2858

@modelcontextprotocol/node

npm i https://pkg.pr.new/@modelcontextprotocol/node@2858

commit: 9b24218