Audit: recurring review findings still introduced by LP/guide creation skills

## Context

Follow-on from #457. Part of the "shift left" track: before changing the creation skills, establish which recurring blocking/structural findings from `review-guide-pr.mdc` are still commonly introduced by [`/create-learning-path`](.cursor/commands/create-learning-path.md) and [`/build-interactive-lj`](.cursor/commands/build-interactive-lj.md).

## Scope

- Review recent review-companion runs (`.cursor/pr-review-state/`) and `review-guide-pr.mdc` findings
- Identify which authoring rules are still commonly violated at creation time, e.g.:
- `navmenu-open` / page requirements
- Section bookends
- Selector stability
- Multistep singleton violations
- Focus-before-formfill
- Secrets `doIt: false`
- Note frequency/severity so the follow-up implementation issue can prioritize

## Deliverable

A short findings doc/summary (no code changes) listing the recurring findings, ranked by frequency and severity.

## Related

Part of epic #577. Split from #457.