fix(adapter): resolve all WHYNOT-WP-0002 drift — designbook-refresh green

Triage the three surfaced divergences the governance-correct way (no stack->React
back-edit, no ir/ hand-edit); make adapt-lit/parity-lit/designbook-refresh now
exit 0:

- PipelineStrip: documented TAG_OVERRIDES in scripts/ir-extract.mjs maps the
  React 'PipelineStrip' to the established tag wn-pipeline (the web-component tag
  is an IR-projection detail, not React-dictated; the component name stays
  faithful). Tag now matches the element; parity tests it (no longer skipped).
- PageHeader.actions: the drift detector now collects each element's named slots
  and treats an IR prop honoured by a same-named slot (<slot name="actions">) as
  satisfied (prop-via-slot, informational) rather than prop-missing.
- Sidebar.current: recorded as an auditable accepted divergence in
  adapters/lit/drift.accepted.json (React monolithic 'current' key vs Lit per-item
  'active' on composable <wn-sidebar-item>) — listed, downgraded to info, not gated.

Rendered surfaces (src/, examples/) untouched — verified zero diff; parity renders
all 10 components green. Adapt/parity outputs idempotent (stable re-run).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

CHANGELOG.md

@@ -25,6 +25,14 @@ Format follows [Keep a Changelog](https://keepachangelog.com/en/1.1.0/). Version
   - `make adapt-plain-css` (T10): a deliberately-unfinished second-adapter **smoke**
     proving the IR/adapter seam — a non-Lit adapter consuming the same `ir/` with the
     same contract shapes and zero `ir/` changes.
+- **Drift triage resolved — `make designbook-refresh` is green** (0 drift, parity pass).
+  The three surfaced divergences were resolved without any stack→React back-edit:
+  a documented `TAG_OVERRIDES` in the extractor maps `PipelineStrip → wn-pipeline`
+  (the tag is an IR-projection detail); the drift detector now recognises a prop
+  honoured by a same-named named slot (`<wn-page-header>` `actions`); and an auditable
+  `adapters/lit/drift.accepted.json` registry records the intentional Sidebar
+  composition divergence (`current` key ↔ per-item `active`) as a justified,
+  non-gating note.
 
 ## [0.4.0] — 2026-06-28