feat(ai-sdk): /retrieve liefert footnotes[] (C-FN Evidence) für Advisor-Workspace

Footnote-Hits werden aus dem Qdrant-Payload (is_footnote/footnote_label/
footnote_verbatim/ref_citation_unit) in interne LegalSearchResult-Felder (json:"-",
kein Pro-Result-Contract-Change) gemappt und im /retrieve-Handler als Top-Level
footnotes[] (Frontend RawFootnote-Shape) herausgezogen; Hits bleiben in results[]
(LLM-Kontext). figures[] als leerer C8-Platzhalter. Speist den Evidence-Workspace
(evidence-adapter.ts) der Frontend-Session.

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

ai-compliance-sdk/internal/ucca/multi_regulation.go

@@ -195,6 +195,11 @@ func hitsToResults(hits []qdrantSearchHit) []LegalSearchResult {
 			ReferencesOut:   getStringSlice(hit.Payload, "references_out"),
 			ReferencesIn:    getStringSlice(hit.Payload, "references_in"),
 			Superseded:      getString(hit.Payload, "status") == "superseded",
+
+			IsFootnote:       getBool(hit.Payload, "is_footnote"),
+			FootnoteLabel:    getString(hit.Payload, "footnote_label"),
+			FootnoteVerbatim: getString(hit.Payload, "footnote_verbatim"),
+			RefCitationUnit:  getString(hit.Payload, "ref_citation_unit"),
 		}
 	}
 	return results