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

[squarepots]

Refs #2.

What

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

• pin 2026-07-28 to the released spec commit;
• read the released schema and example corpus instead of schema/draft;
• regenerate the 2026 anchor, schema twin, fixture manifest, and corpus from the same released source;
• carry the final SubscriptionsListenResultMetaObject and SubscriptionsListenResultResponse spec delta into the reference/parity layer;
• give each schema twin its own source commit;
• align the existing 2025 anchor provenance header with its configured release pin;
• remove the stale nightly workflow that still refreshes released 2026 from draft;
• update the lifecycle documentation to match the resulting invariants.

The public SDK SubscriptionsListenResultMeta name is unchanged. The spec rename is confined to the vendored reference/parity surface.

Why

2026-07-28 is released, but the repository still treats it as a draft-tracking revision. The nightly job refreshes only the generated anchor, while the repository requires the anchor, schema twin, and example corpus to move together.

That mismatch has repeatedly recreated oracle drift. The released revision should have one immutable authority and no draft refresh producer.

Validation

Passed on the fork PR head:

• check:all (typecheck, lint, formatting, docs checks);
• build:all and distribution type smoke test;
• Node 20/22/24 test suites;
• Node 20/22/24 e2e suites;
• Bun and Deno runtime suites;
• client and server conformance;
• examples build + e2e and guide examples.

Publish Any Commit reaches the publish step after building the packages, then fails because the pkg-pr-new GitHub App is not installed on this fork. That is fork infrastructure, not a code failure.

Full audit and scope: #1.