feat: direct fact checks consult registered providers

Checking a FACT relation directly (rt.check('u:1', 'owns', 'doc:9')) now
runs the provider-retrieval pipeline instead of returning 0 without ever
consulting the registered provider. The retrieval set for a direct fact
check is the fact itself (plus, for evidence checks, the injectable deps as
before). The result reports requiredFacts/providedFacts/missingFacts for the
fact, and missingFacts surfaces 'no_provider' when neither a provider nor an
edge can satisfy the check.

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@arbiter/evidence-dsl",
-  "version": "1.7.0",
+  "version": "1.8.0",
   "description": "Evidence DSL v2 compiler: translates the natural Evidence DSL (ADR-000) into @arbiter/core relation configurations.",
   "license": "ISC",
   "type": "module",