chore: attribute rrweb changes to posthog-js in changeset hygiene

[marandaneto]

Problem

The changeset hygiene bot asks for rrweb changesets, but packages under packages/rrweb/ ship with posthog-js and do not need their own changesets.

Example: #4808 (comment)

Changes

Add .changeset/hygiene.json to map all source paths under packages/rrweb/ to posthog-js. This removes the separate rrweb requirement while still checking for a browser SDK changeset. Other packages keep their existing checks.

Pin the shared hygiene script to the implementation in PostHog/.github#74. Merge that PR first. The pin points to its exact implementation commit.

Validation:

• All 14 shared-script regression tests pass.
• Tested against PR perf(replay): deduplicate pending mirror removal roots #4808's actual head in a temporary detached worktree. The missing rrweb warning appears without the mapping and disappears with it.
• JSON formatting, workflow YAML parsing, pre-commit hooks, and git diff --check pass.
• The shared implementation passed Pi autoreview. A separate review of this PR was skipped because it only changes hygiene metadata and a workflow script pin.

Release info Sub-libraries affected

Libraries affected

None. This only changes PR automation and does not need an SDK changeset.

Checklist

• Tests for new code (in the shared-script PR)
• Accounted for the impact of any changes across different platforms
• Accounted for backwards compatibility of any changes (no breaking changes!)
• Took care not to unnecessarily increase the bundle size

If releasing new changes

Not applicable. No published package changes.

🤖 Agent context

Autonomy: Human-driven (agent-assisted)

Implemented with Pi using file tools, Git, GitHub CLI, Node tests, and autoreview for the shared script. rrweb paths are mapped to the browser SDK rather than ignored, so changes still require the changeset for the package that ships them. Human review is required.

[github-actions]

📝 No Changeset Found

This PR doesn't include a changeset. A changeset is required to release a new version.

How to add a changeset

Run this command and follow the prompts:

pnpm changeset

Remember: Never use major version bumps for posthog-js as it's autoloaded by clients.