feat(iace): norm cross-reference matrix, batch 1 (ISO/DIN/ANSI/GB/JIS — 100 entries)

Adds a jurisdiction-cross-reference layer to the norms library. Each entry
maps an ISO/IEC/EN norm to its identifier in DIN (DE), ANSI/NFPA/UL/OSHA (US),
GB (CN), and JIS (JP), with explicit Relation (identical/equivalent/partial/
superseded_by/supersedes) and Confidence (verified/high/medium/low) fields.

Batch 1 covers IDs 1-100 in load order:
  - 1a (50): A-norms + B1-norms + early B2-norms (ergonomics, vibration, noise)
  - 1b (50): remaining B2 (ATEX, EMC, cybersec) + first C-norms (presses,
    robots, conveyors, plastics, woodworking)

These are the foundational, internationally harmonized standards with the
strongest verified mappings (ISO 12100 ~> GB 15706 ~> JIS B 9700, EN 60204-1
~> NFPA 79 ~> GB 5226.1 ~> JIS B 9960-1, etc.).

API:
  - GET /iace/norms-library?include_crossref=true  → inline crossref
  - GET /iace/norms-library/:id/crossref           → single norm lookup
  - GET /iace/norms-library/crossref               → bulk dump

Strategic context: enables dual-use CE/US/CN/JP tech files without
re-authoring, and addresses the "Norm Translation Matrix" gap that the
US-export strategy memory entry calls out. 6 batches remaining (~571 norms)
to reach full library coverage.

Tests: 6 new tests; all pass via `go test -vet=off ./internal/iace/`.
(vet=off needed only to bypass an unrelated pre-existing typo in
 document_export_sources.go.)

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

ai-compliance-sdk/internal/api/handlers/iace_handler_norms.go

@@ -46,6 +46,8 @@ func (h *IACEHandler) ListNormsLibrary(c *gin.Context) {
 	allNorms = append(allNorms, iace.GetWave3dHvacCNorms()...)
 	allNorms = append(allNorms, iace.GetFinalCNorms()...)
 
+	includeCrossRef := c.Query("include_crossref") == "true"
+
 	var filtered []iace.NormReference
 	for _, norm := range allNorms {
 		if normType != "" && norm.NormType != normType {
@@ -54,6 +56,12 @@ func (h *IACEHandler) ListNormsLibrary(c *gin.Context) {
 		if hazardCat != "" && !containsString(norm.HazardCats, hazardCat) {
 			continue
 		}
+		if includeCrossRef {
+			cr := iace.GetNormCrossRef(norm.ID)
+			if len(cr.Mappings) > 0 {
+				norm.CrossRef = &cr
+			}
+		}
 		filtered = append(filtered, norm)
 	}
 
@@ -61,9 +69,36 @@ func (h *IACEHandler) ListNormsLibrary(c *gin.Context) {
 		filtered = []iace.NormReference{}
 	}
 
+	covered, total := iace.CrossRefCoverage(len(allNorms))
 	c.JSON(http.StatusOK, gin.H{
 		"norms": filtered,
 		"total": len(filtered),
+		"crossref_coverage": gin.H{
+			"covered":     covered,
+			"total_norms": total,
+		},
+	})
+}
+
+// GetNormCrossRef handles GET /norms-library/:id/crossref
+// Returns the international cross-reference (DIN/ANSI/GB/JIS/...) for a single norm.
+func (h *IACEHandler) GetNormCrossRef(c *gin.Context) {
+	normID := c.Param("id")
+	if normID == "" {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "norm id required"})
+		return
+	}
+	cr := iace.GetNormCrossRef(normID)
+	c.JSON(http.StatusOK, cr)
+}
+
+// ListNormCrossRefs handles GET /norms-library/crossref
+// Returns the entire cross-reference matrix (all populated entries).
+func (h *IACEHandler) ListNormCrossRefs(c *gin.Context) {
+	entries := iace.ListNormCrossRefs()
+	c.JSON(http.StatusOK, gin.H{
+		"entries": entries,
+		"total":   len(entries),
 	})
 }