docs(releases): draft the 17.5.0 release notes and upgrade checklist (#20396)

## What this is

A pre-cut draft of the curated release page for **17.5.0**,
`content/docs/releases/v17/17-5.mdx`, plus its entry in
`content/docs/releases/v17/meta.json` and in
`scripts/docs-audit/handwritten-docs.json`. Docs-only; no code, no
changeset (`skip-changeset`: the page is the release-time compilation of
the changesets, per `docs/releases-maintenance.md` §3, and publishes
nothing from any package).

It follows the 17.4.0 page's structure: Highlights → What's new →
Breaking changes & migration (triaged, not exhaustive) → New
capabilities → Notable fixes → New in Console (Studio) → Upgrade
checklist (every line marked *not exercised*).

## How it was compiled

- **Source:** all 868 changesets pending on `main` at `ab6fb027` (866 at
`15bf186f` plus two text-only `patch` entries landed since). Every
changeset was read in full and triaged into breaking / new / fix /
internal, with PR numbers and short SHAs taken from the commit that
added each changeset.
- **Citations:** 28 PR numbers carried by those commits' squash subjects
answer 404 on the board (`check:issue-citations`, allocated-but-absent).
The page cites the resolvable commit SHA for those instead and guesses
no replacement number. (The second commit's message says 26; 28 is the
correct count — 3 fixed by hand, 25 by script.)
- **Cross-check:** the 18 ADR-0087 conversions added to
`packages/spec/src/conversions/registry.ts` since the 17.4.0 version
commit (`7e633700`), all registered under protocol major 18, are each
covered by a migration entry on the page.
- **Console section:** built from the three pin-bump changesets
(`53ded82bf7a4 → 87af769e9a3e → 62597c588072 → f8a9d0fb0596`). The first
bump's changeset lists only 100 of its 584 releasing objectui entries,
and the page says so.
- Two reconciliations recorded on the page: `translation-target-unknown`
becomes an `error` in **17.5.0** (the 17.4.0 lint CHANGELOG carries no
such change, despite one changeset saying "since 17.4.0"); and the
organization `metadata` change (#19122) is listed as a wire-type change
even though its changeset declares a widening.

## Deliberately not in this PR

- `content/docs/releases/v17/index.mdx` is **untouched**. Its
release-status blockquote and per-release list must only claim 17.5.0
after it ships, so that edit belongs at release time.
- An MDX comment at the top of `17-5.mdx` lists the four release-time
edits: publish date, changesets landed after `ab6fb027`, the per-package
CHANGELOG entry count, and the `v17/index.mdx` update.

**Landing:** the maintainer decided (2026-09-28) to land this page
before the 17.5.0 cut. The four release-time edits above follow in a
separate docs-only PR once 17.5.0 is on npm; until then the docs site
shows the 17.5.0 page ahead of the release.

## Verification

Run locally on the head commit, with the workspace installed:

- `check:doc-anchors`, `check:issue-citations`, `check:role-word`,
`check:docs-audit-scope` — the four gates the first push failed or would
have failed — now pass.
- Also passing: `check:nul-bytes`, `check:doc-authoring`,
`check-doc-frontmatter`, `check-docs-nav-label`, `check:docs-single-h1`,
`check:docs-redirects`, `check:docs-locale-catch-all`,
`check-doc-route-spelling --advisory`, `check-docs-section-name`,
`check:published-readme-links`, `check:docs-image-tag`,
`check:corpus-claim-drift`, `check-section-landing-index`,
`check:release-notes`, `check:release-page-status`,
`check-release-section-coverage` (plain and `--strict`),
`check:release-body`, `check-scripts-symbol-anchors`.
- The page compiles as MDX with `@mdx-js/mdx` 3 + `remark-gfm`, and all
four tables parse with no ragged rows. On the head commit every CI check
is green, `Lint & Repo Gates` and `Build Docs` included.

---
_Generated by [Claude
Code](https://claude.ai/code/session_014VGCS11YUtYAiinRcdqQwL)_

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Co-authored-by: Claude <noreply@anthropic.com>

Author: hotlong