docs(Rule 40): Add empirical validation showing 33% Google Maps error rate for Type I

Audit of 188 Type I custodian files revealed:
- 62 false matches (33%) detected and corrected
- Categories: domain mismatch (39), name mismatch (8), wrong location (6),
  wrong org type (5), different entity (3), different event (3)
- Documents why Google Maps fails for intangible heritage:
  virtual orgs, person-based heritage, volunteer networks, event-based orgs

This validates KIEN as TIER_1_AUTHORITATIVE for Type I custodians.

.opencode/rules/kien-authoritative-source-rule.md

@@ -4,6 +4,38 @@
 
 For Intangible Heritage Custodians (Type I), the KIEN registry at `https://www.immaterieelerfgoed.nl/` is the **TIER_1_AUTHORITATIVE** source for contact data and addresses. Google Maps enrichment is **TIER_3_CROWD_SOURCED** and should NEVER override KIEN data.
 
+## Empirical Validation (January 2025)
+
+A comprehensive audit of 188 Type I custodian files revealed:
+
+| Category | Count | Percentage |
+|----------|-------|------------|
+| ✅ Google Maps matches OK | 101 | 53.7% |
+| 🔧 **FALSE_MATCH detected** | **62** | **33.0%** |
+| ⚠️ No official website (valid) | 20 | 10.6% |
+| 📭 No Google Maps data | 5 | 2.7% |
+
+**Key Finding: 33% of Google Maps enrichment data for Type I custodians was incorrect.**
+
+### False Match Categories Identified
+
+1. **Domain mismatches** (39 files): Google Maps website ≠ KIEN official website
+2. **Name mismatches** (8 files): Completely different organizations (e.g., "Ria Bos" heritage practitioner → "Ria Money Transfer Agent")
+3. **Wrong location** (6 files): Same-ish name but different city (Amsterdam→Den Haag, Netherlands→Suriname!)
+4. **Wrong organization type** (5 files): Federation vs specific member, heritage org vs webshop
+5. **Different entity type** (3 files): Organization vs location/street name
+6. **Different event** (3 files): Horse racing vs festival, different village's event
+
+### Why Google Maps Fails for Type I
+
+Google Maps is optimized for commercial businesses with physical storefronts. Type I intangible heritage custodians are fundamentally different:
+
+- **Virtual organizations** without commercial presence
+- **Person-based heritage** (individual practitioners preserving traditional crafts)
+- **Volunteer networks** meeting in private residences
+- **Event-based organizations** that exist only during festivals
+- **Federations** that coordinate member organizations without own premises
+
 ## Rationale
 
 Google Maps frequently returns **false matches** for intangible heritage organizations because: