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>

adapters/lit/drift/PageHeader.md

@@ -1,9 +1,9 @@
 <!-- @generated by make adapt-lit (WHYNOT-WP-0002 T07) — overwritten each run; do not hand-edit. -->
 # Drift — PageHeader `<wn-page-header>`
 
-**Status:** drift — ⚠ drift detected — resolve per `.claude/rules/designbook-propagation.md`.
+**Status:** ok — ✓ in sync with the IR contract.
 
 | severity | kind | prop | detail |
 | --- | --- | --- | --- |
-| **drift** | prop-missing | `actions` | in IR (attribute 'actions'), absent on <wn-page-header> |
+| info | prop-via-slot | `actions` | IR prop honoured by <slot name="actions"> on <wn-page-header> (slotted content, not an attribute). |
 | info | prop-extra | `hasActions` | on <wn-page-header> (attribute 'hasactions'), not in IR contract. |