docs: establish FraudShield constitution v1.0.0

6 core principles: Security-First, Explainability, Test-First,
Observability, Data Privacy by Design, Simplicity (YAGNI).
Includes Security & Compliance, Development Workflow, and Governance sections.

.specify/extensions/.registry

@@ -0,0 +1,23 @@
+{
+  "schema_version": "1.0",
+  "extensions": {
+    "git": {
+      "version": "1.0.0",
+      "source": "local",
+      "manifest_hash": "sha256:9731aa8143a72fbebfdb440f155038ab42642517c2b2bdbbf67c8fdbe076ed79",
+      "enabled": true,
+      "priority": 10,
+      "registered_commands": {
+        "opencode": [
+          "speckit.git.feature",
+          "speckit.git.validate",
+          "speckit.git.remote",
+          "speckit.git.initialize",
+          "speckit.git.commit"
+        ]
+      },
+      "registered_skills": [],
+      "installed_at": "2026-05-11T22:30:52.716957+00:00"
+    }
+  }
+}