feat(iace): FMEA P1 — open methodology anchors + bp_iace_fmea_kb

P1 of the auto-FMEA build plan: establish the public-domain methodology
foundation (no AIAG-VDA/SAE/IEC tables reproduced).
- fmea_data_sources.go: MIL-STD-882E severity (Cat I-IV→1-10) + probability
  (A-F→1-10 with per-hour λ bands), OccurrenceFromRate(λp·α), SeverityForCategory,
  MIL-STD-1629A CriticalityCm = λp·α·β·t. Own 1-10 projection, government-anchored.
- 4 versioned source docs (MIL-STD-1629A, MIL-STD-882E, NASA RCM, FMD-91/NPRD-91)
  ingested into the new RAG collection bp_iace_fmea_kb (whitelisted).
- Tests for all scales/mappings/criticality (green).

Next (P1 step 2): fetch FMD-91/NPRD-91 bulk λ/α tables from DTIC.

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

ai-compliance-sdk/internal/iace/datasources/fmd91_nprd_failure_modes.md

@@ -0,0 +1,39 @@
+# Failure-mode taxonomy & reliability data — FMD-91 / NPRD-91 (public domain)
+
+Open component→failure-mode taxonomy and failure-rate (λ) / mode-ratio (α)
+anchor for the IACE auto-FMEA. Ingested into `bp_iace_fmea_kb`. The bulk numeric
+tables are fetched from the DTIC PDFs in a follow-up P1 step; this doc fixes the
+sources + the per-component mode lists used to seed the gated library (P2).
+
+## Sources
+- **FMD-91** (RAC/DTIC) — *Failure Mode / Mechanism Distributions* — modes +
+  mechanisms with **% distribution (α)** per part class. **Public domain**
+  ("Approved for Public Release; Distribution Unlimited"). DTIC ADA259655.
+- **NPRD-91 / NPRD-95** (RAC/DTIC) — *Nonelectronic Parts Reliability Data* —
+  field **failure rates λ** for mechanical / electromechanical parts. **Public
+  domain.** DTIC ADA242083.
+- **MIL-HDBK-217F** (US DoD) — electronic-part failure-rate models λ. Public
+  domain (obsolete 1995 but legally free).
+- **Attribution:** `Source: FMD-91 / NPRD-91 (RAC, DTIC), public domain`
+- **AVOID:** Quanterion NPRD-2023 / FMD-2016 / EPRD-2024 (proprietary reissues),
+  OREDA (commercial), FIDES tables (© DGA — read-only), ISO 14224 (copyrighted).
+
+## Failure modes by component class (open — FMD-91 + CC-BY-SA Wikipedia)
+| Component class | Typical failure modes |
+|---|---|
+| Bearings | fatigue spalling/pitting, wear, brinelling, seizure, contamination |
+| Gears | pitting, scuffing/scoring, tooth-fatigue fracture, wear |
+| Shafts / fasteners / springs | fatigue fracture, fretting, loosening, set/relaxation |
+| Seals / hoses / cylinders | leakage (external/internal), extrusion, hardening, rupture |
+| Valves / pumps | stuck-open, stuck-closed, leakage, fail-to-open/close, degraded flow |
+| Motors / contactors | winding short, open circuit, insulation breakdown, contact weld/stick |
+| Sensors / cabling | drift/bias, loss of signal, intermittent, open/short |
+
+FMD-91 additionally gives the **% weighting (α)** of each mode per class — that
+is the mode-ratio in `Cm = λp·α·β·t` and lets the engine RANK modes rather than
+enumerate them flatly.
+
+## How used in IACE
+- Taxonomy → seeds/expands the gated failure-mode library (P2).
+- λ (NPRD/217) × α (FMD-91) → mode rate → `OccurrenceFromRate` → 1–10 occurrence.
+- Each `source`/`license` tagged; allowlist rejects copyrighted/proprietary data.