docs(changelog): amend 1.15.0 notes for the @base-ui/react 1.6.0 → 1.8.0 bump

[interacsean]

Summary

@tailor-platform/app-shell@1.15.0 bumped @base-ui/react from 1.6.0 to 1.8.0 (#517, commit 6e4f783). Its release note said only that Base UI moved to 1.8.0. It gave no from-version and named no behaviour change, but two upstream changes break consumer tests:

1. Select no longer renders its options into the DOM until it is opened, so unit tests that assert option text on a closed Select fail.
2. Opening a Dialog/AlertDialog applies a scroll lock that shifts layout during a Playwright click, so a coordinate click can land on the backdrop and close the dialog.

This PR fixes the notes after the fact and adds a rule so the next UI-foundation bump documents this up front.

• Ticket: https://github.com/tailor-inc/platform-planning/issues/1945
• Source feedback: https://github.com/tailor-professional-service/knowledge/discussions/502

Changes

• packages/core/CHANGELOG.md: amends only the 6e4f783 bullet in the 1.15.0 section. It now gives 1.6.0 → 1.8.0, lists both behaviour changes with the test-side fix, links to the migration entry, and ends with an italic note that the entry was amended after release. No other entry is touched.
• docs/migrations.md: adds a 1.15.0 row and section (applies to / what breaks / how to detect / what to change). An app that changes nothing can still fail CI after upgrading, so it belongs on this page.
• docs-manifest.json: hash refresh from pnpm docs:sync. docs/migrations.md is copied into the bundled skill, and the drift gate needs this.
• .changeset/amber-owls-listen.md: patch changeset. The CHANGELOG inside the published 1.15.0 tarball can't change, so the next release's npm CHANGELOG carries a short pointer instead.
• .agents/skills/create-changeset/SKILL.md: new summary rule. A changeset for a UI-foundation bump (@base-ui/react and similar) must give from→to versions and list the behaviour or test-visible changes found in the PR's snapshot diffs.

No package code or version changes.

Not in this PR: ticket action 6, the version policy question (should a Base UI minor bump be an app-shell minor?). That still needs a maintainer decision.

After merge

Update the GitHub release body for @tailor-platform/app-shell@1.15.0 with the amended section. The current body is the CHANGELOG's 1.15.0 section without its heading, so extract the same range from main:

git fetch origin main
git show origin/main:packages/core/CHANGELOG.md \
  | awk '/^## 1\.15\.0$/{f=1; next} /^## /{f=0} f' > /tmp/app-shell-1.15.0-notes.md
gh release edit "@tailor-platform/app-shell@1.15.0" \
  --repo tailor-platform/app-shell \
  --notes-file /tmp/app-shell-1.15.0-notes.md

The italic "amended after release" note is part of the extracted section, so the release body carries it too.

Checks

• pnpm fmt:check: clean (CHANGELOG.md is excluded from oxfmt by .oxfmtrc.json)
• pnpm docs:check: no blocking issues after pnpm docs:sync

🤖 Generated with Claude Code

[github-actions]

Code Metrics Report

	main (c3e4b52)	#562 (13954bc)	+/-
Coverage	87.5%	87.5%	0.0%
Test Execution Time	2m20s	2m13s	-7s

Details

  |                     | main (c3e4b52) | #562 (13954bc) | +/-  |
  |---------------------|----------------|----------------|------|
  | Coverage            |          87.5% |          87.5% | 0.0% |
  |   Files             |            206 |            206 |    0 |
  |   Lines             |           6082 |           6082 |    0 |
  |   Covered           |           5323 |           5323 |    0 |
+ | Test Execution Time |          2m20s |          2m13s |  -7s |

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Reported by octocov