docs: add release notes preparation guide (#1575)

## Summary
- Add `.claude/skills/release-notes.md` documenting the workflow for
preparing release notes (find cutoff, collect changes from this repo +
upstream microsoft/playwright, write `release-notes.md`, create draft
release).
- Reference the guide from `CLAUDE.md`.

Author: yury-s

.claude/skills/release-notes.md

@@ -0,0 +1,49 @@
+---
+name: release-notes
+description: Prepare GitHub release notes for playwright-mcp by combining changes from this repo and upstream microsoft/playwright since the last release.
+---
+
+# Preparing Release Notes
+
+Most MCP source lives upstream at `~/playwright/packages/playwright-core/src/tools/` (and `tests/mcp/`). Release notes need to combine changes from both repos.
+
+## 1. Find the cutoff
+
+```bash
+# Last published release and its date
+gh release list --repo microsoft/playwright-mcp --limit 5
+
+# Format reference — use the most recent non-trivial release
+gh release view v0.0.69 --repo microsoft/playwright-mcp
+
+# Playwright version that shipped in the last release
+git show <release-commit>:package.json | grep -E '"playwright|"@playwright"'
+# Convert the alpha timestamp to a UTC date for the upstream log filter
+date -r <timestamp_seconds> -u
+```
+
+## 2. Collect changes
+
+```bash
+# Upstream playwright (MCP code path widened to catch tools/cli/dashboard too)
+cd ~/playwright
+git log --since="<UTC date>" --oneline -- packages/playwright-core/src/tools/
+
+# This repo
+cd -
+git log <last-release-commit>..HEAD --oneline
+```
+
+Filter for `feat(mcp)`, `fix(mcp)`, `feat(extension)`, `fix(extension)`. Many extension PRs land in *both* repos because the extension source lives upstream now — prefer the `microsoft/playwright` PR link. Use `git show <sha> --stat` to disambiguate when a commit subject is ambiguous.
+
+## 3. Write `release-notes.md`
+
+Follow the format from the prior release: `## What's New` (with `### New Tools`, `### Tool Improvements`, optional `### Browser Extension`, `### Other Changes`) and `## Bug Fixes`. Link each entry to its PR (`[#NNNNN](https://github.com/microsoft/playwright/pull/NNNNN)` or the playwright-mcp equivalent). Skip purely internal refactors, dep bumps, repo layout changes, and anything not user-visible. **Do not mention features that are not yet enabled by default** — confirm with the user before listing experimental flags.
+
+## 4. Create draft release
+
+```bash
+gh release create v0.0.<next> --repo microsoft/playwright-mcp \
+  --draft --title "v0.0.<next>" --target main \
+  --notes-file release-notes.md
+```

CLAUDE.md

@@ -29,3 +29,6 @@ EOF
 Never add Co-Authored-By agents in commit message.
 Branch naming for issue fixes: `fix-<issue-number>`
 
+## Preparing Release Notes
+
+See [.claude/skills/release-notes.md](.claude/skills/release-notes.md).