datalog: dl-query accepts conjunctive goal lists (167/167)

dl-query now auto-dispatches on the first element's shape:
- positive literal (head is a symbol) or {:neg ...} dict → wrap
- list of literals → conjunctive query

dl-query-coerce normalizes; dl-query-user-vars collects the union
of user-named vars (deduped, '_' filtered) for projection. Old
single-literal callers unchanged.

  (dl-query db '(p X))                   ; single
  (dl-query db '((p X) (q X)))           ; conjunction
  (dl-query db (list '(n X) '(> X 2)))   ; with comparison

2 new api tests cover multi-goal AND and conjunction with comparison.

lib/datalog/scoreboard.json

@@ -1,8 +1,8 @@
 {
   "lang": "datalog",
-  "total_passed": 165,
+  "total_passed": 167,
   "total_failed": 0,
-  "total": 165,
+  "total": 167,
   "suites": [
     {"name":"tokenize","passed":26,"failed":0,"total":26},
     {"name":"parse","passed":18,"failed":0,"total":18},
@@ -12,8 +12,8 @@
     {"name":"semi_naive","passed":8,"failed":0,"total":8},
     {"name":"negation","passed":10,"failed":0,"total":10},
     {"name":"aggregates","passed":16,"failed":0,"total":16},
-    {"name":"api","passed":9,"failed":0,"total":9},
+    {"name":"api","passed":11,"failed":0,"total":11},
     {"name":"demo","passed":13,"failed":0,"total":13}
   ],
-  "generated": "2026-05-08T09:12:57+00:00"
+  "generated": "2026-05-08T09:16:59+00:00"
 }