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/parity.mjs

@@ -24,7 +24,7 @@ import { readFileSync, readdirSync, existsSync, mkdirSync, writeFileSync, rmSync
 import { spawn } from "node:child_process";
 import { join, dirname } from "node:path";
 import { fileURLToPath } from "node:url";
-import { parseLitElements, componentDrift } from "./scaffold.mjs";
+import { parseLitElements, componentDrift, loadAccepted } from "./scaffold.mjs";
 
 const REPO = join(dirname(fileURLToPath(import.meta.url)), "..", "..");
 const IR_COMPONENTS = join(REPO, "ir", "components");
@@ -96,13 +96,14 @@ async function main() {
     // type-coercion false positives). The browser then confirms the element
     // actually upgrades + renders — the thing static analysis cannot prove.
     const byTag = parseLitElements(REPO);
+    const accepted = loadAccepted(REPO);
 
     const results = [];
     for (const c of contracts) {
       const tag = c.tag;
-      const drift = componentDrift(c, byTag);
-      const attrMismatch = drift.issues.filter((i) => i.kind === "attribute-mismatch");
-      const missing = drift.issues.filter((i) => i.kind === "prop-missing");
+      const drift = componentDrift(c, byTag, accepted);
+      const attrMismatch = drift.issues.filter((i) => i.kind === "attribute-mismatch" && i.severity === "drift");
+      const missing = drift.issues.filter((i) => i.kind === "prop-missing" && i.severity === "drift");
       const hasDefaultSlot = (c.slots || []).some((s) => s.name === "default");
 
       const observed = await page.evaluate(async ({ tag, attrs, hasDefaultSlot }) => {