feat(advisor): evidence-framed header + bindingness contract seam

Rework the Compliance Advisor header ("Diese Antwort stuetzt sich auf")
to describe the EVIDENCE rather than the documents: binding
Rechtsgrundlagen split from Leitlinien (soft-law guidance), a
per-regulation breakdown, plus Abbildungen, Fussnoten and Evidence Units.
No fabricated trust score — objective counts only.

- bindingness is a canonical Legal-KG fact (APEX rule): added an optional
  EvidenceUnit.bindingness contract seam; the FE renders the split from it
  and degrades to a neutral per-regulation breakdown when it is absent
  (SDK/RAG asked via board to populate it in /retrieve).
- evidence-grouping.ts: pure, tested grouping/counting model.
- route.ts: optional `audience` field (tonality) kept out of the retrieval
  question; answers lead with a "Kurz gesagt" summary, structured by theme.
- E2E + unit tests updated for the evidence framing.

Not deployed.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

admin-compliance/e2e/specs/compliance-advisor.spec.ts

@@ -40,7 +40,7 @@ const ANSWER = {
   clarity: { is_underspecified: false, dominant_context: 'cyber', concentration: 0.88 },
   answer: 'Die Meldung erfolgt unverzüglich [1].',
   evidence: [
-    { evidence_id: 'e1', document: 'CRA', section: 'Art. 14', paragraph: 'Abs. 1', snippet: 'unverzüglich melden' },
+    { evidence_id: 'e1', document: 'CRA', section: 'Art. 14', paragraph: 'Abs. 1', snippet: 'unverzüglich melden', bindingness: 'binding' },
   ],
   citations: [
     { citation_id: 'c1', number: 1, evidence_id: 'e1', document: 'CRA', section: 'Art. 14', paragraph: 'Abs. 1' },
@@ -77,7 +77,10 @@ test.describe('Compliance Advisor — Clarity Gate', () => {
 
     await expect(sdkPage.getByText(/unverzüglich/)).toBeVisible()
     await expect(sdkPage.getByTitle('Beleg 1 anzeigen')).toBeVisible()
-    await expect(sdkPage.getByText('Cyber Resilience Act (CRA)')).toBeVisible()
+    // bindingness present -> header splits into Rechtsgrundlagen vs Leitlinien (evidence framing)
+    await expect(sdkPage.getByText('Rechtsgrundlagen').first()).toBeVisible()
+    // family name resolved for the user (shown both in the summary breakdown and the evidence card)
+    await expect(sdkPage.getByText('Cyber Resilience Act (CRA)').first()).toBeVisible()
   })
 
   test('clarify -> pick a context -> scoped answer', async ({ sdkPage }) => {