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/lib/sdk/advisor/evidence-grouping.ts

@@ -0,0 +1,80 @@
+// Pure grouping/counting for the "Diese Antwort stützt sich auf" evidence header. No React, testable.
+// Splits evidence into binding norms (Kernnormen) vs. soft-law guidance (Leitlinien) using the
+// Legal-KG-owned `bindingness` fact (APEX rule) — the FE never derives bindingness itself. When the
+// fact is absent it degrades to a neutral per-regulation breakdown (no norm/guidance labels, no
+// fabricated legal classification).
+
+import type { EvidenceUnit } from './contract'
+import { resolveRegulation } from './regulation-display'
+
+export type Bindingness = 'binding' | 'guidance' | 'unknown'
+
+export interface FamilyGroup {
+  key: string // stable family key (grouping)
+  label: string // human-readable regulation name
+  sections: string[] // distinct provisions in first-seen order (e.g. "Art. 13", "§ 25")
+  units: number // raw evidence units in this family
+  bindingness: Bindingness
+}
+
+export interface EvidenceSummaryModel {
+  groups: FamilyGroup[]
+  norms: FamilyGroup[] // bindingness === 'binding'
+  guidance: FamilyGroup[] // bindingness === 'guidance'
+  other: FamilyGroup[] // bindingness unknown
+  hasBindingness: boolean // at least one unit carries the Legal-KG fact
+  normProvisions: number // distinct binding provisions (Kernnormen)
+  guidanceCount: number // distinct guidance documents (Leitlinien)
+  unitCount: number // total evidence units
+}
+
+export function groupByFamily(evidence: EvidenceUnit[]): FamilyGroup[] {
+  const byKey = new Map<string, FamilyGroup>()
+  for (const e of evidence) {
+    const { familyKey, familyLabel } = resolveRegulation({
+      code: e.regulation_code || e.document,
+      short: e.document,
+    })
+    let g = byKey.get(familyKey)
+    if (!g) {
+      g = { key: familyKey, label: familyLabel, sections: [], units: 0, bindingness: 'unknown' }
+      byKey.set(familyKey, g)
+    }
+    g.units += 1
+    if (e.section && !g.sections.includes(e.section)) g.sections.push(e.section)
+    if (e.bindingness && g.bindingness === 'unknown') g.bindingness = e.bindingness
+  }
+  return [...byKey.values()]
+}
+
+/** distinct provisions for a family; falls back to raw unit count when no section is known. */
+export function provisionCount(g: FamilyGroup): number {
+  return g.sections.length || g.units
+}
+
+/** "5 Artikel" / "§ 25" / "3 Fundstellen" — the noun follows the family's own citation style. */
+export function provisionSummary(g: FamilyGroup): string {
+  const n = g.sections.length
+  if (n === 0) return `${g.units} ${g.units === 1 ? 'Fundstelle' : 'Fundstellen'}`
+  if (n === 1) return g.sections[0]
+  if (g.sections.every((s) => /^\s*art/i.test(s))) return `${n} Artikel`
+  if (g.sections.every((s) => s.trim().startsWith('§'))) return `${n} §§`
+  return `${n} Fundstellen`
+}
+
+export function summarizeEvidence(evidence: EvidenceUnit[]): EvidenceSummaryModel {
+  const groups = groupByFamily(evidence)
+  const norms = groups.filter((g) => g.bindingness === 'binding')
+  const guidance = groups.filter((g) => g.bindingness === 'guidance')
+  const other = groups.filter((g) => g.bindingness === 'unknown')
+  return {
+    groups,
+    norms,
+    guidance,
+    other,
+    hasBindingness: norms.length > 0 || guidance.length > 0,
+    normProvisions: norms.reduce((n, g) => n + provisionCount(g), 0),
+    guidanceCount: guidance.length,
+    unitCount: evidence.length,
+  }
+}