feat(ai-sdk): demote superseded pre-eu-v1 sources in authority rerank

The old pre-eu-v1 corpus chunks (un-annotated CRA/AI Act/DORA/NIS2/DSGVO
duplicates + the old Machinery Directive and its guide) are tagged
status=superseded / use_for_primary=false in the vector store. Honor that
in the rerank: a superseded result takes a fixed penalty so the eu-v1 norm
wins default questions, while the old source stays in the pool (demoted,
not hidden) and remains findable for history / transition questions.

Verified on dev: "CRA Sicherheitsupdates" now returns CRA Anhang I (eu-v1)
at #1 instead of an un-annotated old chunk; MaschinenVO outranks the old
Machinery Directive/guide; superseded chunks remain retrievable lower down.

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

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

@@ -4,14 +4,15 @@ import "sort"
 
 // Re-ranking coefficients (validated in the offline golden harness; Phase A — conservative).
 const (
-	authorityCoef    = 0.40 // * weight/100
-	jurisdictionGain = 0.05 // binding/guidance from DE or EU
-	foreignPenalty   = 0.60 // foreign law on a DE/EU question (demoted, not removed)
-	unknownPenalty   = 0.08
-	domainMatchGain  = 0.15
-	offDomainPenalty = 0.10 // off-domain binding (demoted, not removed)
-	scopePenalty     = 0.25 // BDSG Teil 3 (law enforcement) on a general DP question
-	topicGain        = 0.18 // amplifier only
+	authorityCoef     = 0.40 // * weight/100
+	jurisdictionGain  = 0.05 // binding/guidance from DE or EU
+	foreignPenalty    = 0.60 // foreign law on a DE/EU question (demoted, not removed)
+	unknownPenalty    = 0.08
+	domainMatchGain   = 0.15
+	offDomainPenalty  = 0.10 // off-domain binding (demoted, not removed)
+	scopePenalty      = 0.25 // BDSG Teil 3 (law enforcement) on a general DP question
+	topicGain         = 0.18 // amplifier only
+	supersededPenalty = 0.50 // superseded Alt-Quelle (pre-eu-v1): demoted, nicht versteckt
 )
 
 // authorityScore computes the normative relevance of a result for a query. It augments the
@@ -20,6 +21,12 @@ func authorityScore(query string, r LegalSearchResult, qDomain string, qForeign
 	info := classifyAuthority(r)
 	score := r.Score + authorityCoef*float64(info.weight)/100.0
 
+	if r.Superseded {
+		// Alt-Quelle (pre-eu-v1): Default-Fragen sollen die eu-v1-Norm sehen. Demoted,
+		// nicht entfernt — fuer Historie/Uebergangsfragen bleibt sie auffindbar.
+		score -= supersededPenalty
+	}
+
 	if info.jurisdiction == "CH" && !qForeign {
 		score -= foreignPenalty // Fremdrecht bei DE/EU-Frage: demoted, nicht geloescht
 	} else {