feat(iace): unified FailureKnowledge ontology + NASA starter (FMEA P2)

The source-agnostic failure ontology shared by the FMEA library and the CE
hazard side: Component → FailureMode → Mechanism → Effect → Hazard → Harm →
Control, each row source+licence tagged. A licence ALLOWLIST
(FailureKnowledgeLicenseAllowed) rejects copyrighted/proprietary/NC sources
up front (© IITRI, DIN/ISO, AIAG, OREDA, CC-BY-NC) — the discipline learned
from the FMD-91/NPRD-91 licence finding.

Seeded with a curated NASA NTRS lessons-learned starter (5 real entries,
public domain). GET /iace/failure-knowledge (+ ?domain=). Tests pin the
governance invariant: every entry must carry a commercially-usable licence.

Next: Playwright+OCR bulk loader (NTRS API → PDF/OCR → tuple extraction) to
grow the corpus from NASA/OSHA/CPSC/MAUDE/NTSB.

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

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

@@ -0,0 +1,29 @@
+package handlers
+
+import (
+	"net/http"
+
+	"github.com/breakpilot/ai-compliance-sdk/internal/iace"
+	"github.com/gin-gonic/gin"
+)
+
+// ListFailureKnowledge handles GET /failure-knowledge.
+// Read-only unified failure-knowledge ontology (Component → FailureMode →
+// Mechanism → Effect → Hazard → Harm → Control) curated from commercially-usable
+// open sources (currently NASA NTRS, public domain). Optional ?domain= filter.
+// This is the shared corpus that seeds the FMEA library and the CE hazard side.
+func (h *IACEHandler) ListFailureKnowledge(c *gin.Context) {
+	var items []iace.FailureKnowledge
+	if d := c.Query("domain"); d != "" {
+		items = iace.FailureKnowledgeByDomain(d)
+	} else {
+		items = iace.AllFailureKnowledge()
+	}
+	if items == nil {
+		items = []iace.FailureKnowledge{}
+	}
+	c.JSON(http.StatusOK, gin.H{
+		"failure_knowledge": items,
+		"total":             len(items),
+	})
+}