artdag: Phase 2 Analyze on Datalog + 16 tests

analyze.sx projects DAG edges to (edge in out) facts and runs recursive
reachable rules for deps-of/dependents-of/reachable-from/ancestors-of, plus
dirty-closure (dirty(Y):-edge(X,Y),dirty(X)) for incremental recompute. Keystone:
changing a mid node dirties only it + downstream. analyze 16/16, total 36/36.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

lib/artdag/scoreboard.json

@@ -1,8 +1,9 @@
 {
   "suites": {
-    "dag": {"pass": 20, "fail": 0}
+    "dag": {"pass": 20, "fail": 0},
+    "analyze": {"pass": 16, "fail": 0}
   },
-  "total_pass": 20,
+  "total_pass": 36,
   "total_fail": 0,
-  "total": 20
+  "total": 36
 }