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.

tests/DSLRuntimeExt.test.js

@@ -144,4 +144,25 @@ describe('DSLRuntime extended', () => {
     rt.updateNodeData('doc:9', { created: '2026-08-03T00:00:00Z' });
     assert.throws(() => rt.addNode('doc:8', 'Doc', { created: {} }), /must be timestamp/);
   });
+
+  it('direct FACT checks consult the registered provider', async () => {
+    const rt = makeRuntime();
+    rt.addNode('u:1', 'Employee', {});
+    rt.addNode('doc:9', 'Doc', {});
+    let calls = 0;
+    rt.registerFact('owns', async () => { calls++; return 0.9; });
+    // Checking the fact directly (not via an evidence) must retrieve it.
+    const res = await rt.check('u:1', 'owns', 'doc:9');
+    assert.equal(res.possibility, 0.9);
+    assert.equal(calls, 1);
+    assert.deepEqual(res.requiredFacts, ['owns']);
+    assert.deepEqual(res.providedFacts, ['owns']);
+    // Without a provider and without an edge, it reports the missing fact.
+    const rt2 = new DSLRuntime(new Arbiter()).compile(BASE_DSL, 'rt-fact-miss');
+    rt2.addNode('u:1', 'Employee', {});
+    rt2.addNode('doc:9', 'Doc', {});
+    const missed = await rt2.check('u:1', 'owns', 'doc:9');
+    assert.equal(missed.possibility, 0);
+    assert.deepEqual(missed.missingFacts, [{ relation: 'owns', reason: 'no_provider' }]);
+  });
 });