Complete WP-0003 T06 pilot validation and sync credential routing docs

Close the dangling MVP pilots task with H1 provider-switch test, pilot
validation report, and resolver tenant-override fix. Add credential routing
guidance to AGENTS.md and Claude rules.

src/feature_control_sdk/resolver.py

@@ -81,8 +81,9 @@ class Resolver:
             reason = "entitlement_missing"
             source = "entitlement_rule"
             value = definition.safe_fallback
-        elif tenant and self.values.get(f"tenant:{tenant}:{key}") is not None:
+        elif tenant and f"tenant:{tenant}:{key}" in self.values:
             # tenant override
+            value = self.values[f"tenant:{tenant}:{key}"]
             state = "enabled" if value else "disabled"
             reason = "tenant_policy"
             source = "tenant_rule"