revert(cypher): drop the early-WHERE deferral that #2253 superseded

The early WHERE pass in execute_single runs on seed rows where only the
first alias is bound, so a NOT on the target node or the relationship
pruned every row (#2250). This branch fixed that by skipping the early
pass until every alias the WHERE reads was bound.

While it waited for review, #2253 (8ab555ee) landed the same fix on
main as a three-valued early pass: an unbound alias is UNKNOWN, NOT
keeps it UNKNOWN, and only a definite FALSE prunes. This branch's
regression tests pass on main's production code unchanged, so restore
src/cypher/cypher.c to the branch's base and keep the tests; the merge
of main that follows takes main's implementation.

Signed-off-by: Martin Vogel <martin.vogel.tech@gmail.com>

src/cypher/cypher.c

@@ -4145,54 +4145,7 @@ static void execute_with_simple(cbm_return_clause_t *wc, binding_t *bindings, in
     }
 }
 
-static bool condition_bindings_available(const cbm_condition_t *condition, binding_t *binding) {
-    if (condition->variable && !binding_get(binding, condition->variable) &&
-        !binding_get_edge(binding, condition->variable)) {
-        return false;
-    }
-    for (int i = 0; i < condition->arg_count; i++) {
-        const char *var = condition->args[i].variable;
-        if (var && !binding_get(binding, var) && !binding_get_edge(binding, var)) {
-            return false;
-        }
-    }
-    return true;
-}
-
-static bool expr_bindings_available(const cbm_expr_t *expr, binding_t *binding) {
-    if (!expr) {
-        return true;
-    }
-    switch (expr->type) {
-    case EXPR_CONDITION:
-        return condition_bindings_available(&expr->cond, binding);
-    case EXPR_AND:
-    case EXPR_OR:
-    case EXPR_XOR:
-        return expr_bindings_available(expr->left, binding) &&
-               expr_bindings_available(expr->right, binding);
-    case EXPR_NOT:
-        return expr_bindings_available(expr->left, binding);
-    }
-    return false;
-}
-
-static bool where_bindings_available(const cbm_where_clause_t *where, binding_t *binding) {
-    if (!where) {
-        return true;
-    }
-    if (where->root) {
-        return expr_bindings_available(where->root, binding);
-    }
-    for (int i = 0; i < where->count; i++) {
-        if (!condition_bindings_available(&where->conditions[i], binding)) {
-            return false;
-        }
-    }
-    return true;
-}
-
-/* Apply a WHERE filter after its referenced variables have been bound. */
+/* Apply post-WITH WHERE filter */
 static void filter_bindings_where(const cbm_where_clause_t *where, binding_t *vbindings,
                                   int *vcount) {
     int kept = 0;
@@ -5196,8 +5149,7 @@ static int execute_single(cbm_store_t *store, cbm_query_t *q, const char *projec
         binding_t b = {0};
         b.store = store;
         binding_set(&b, var_name, &scanned[i]);
-        bool pass = !q->where || !where_bindings_available(q->where, &b) ||
-                    eval_where(q->where, &b);
+        bool pass = !q->where || eval_where(q->where, &b);
         if (pass) {
             bindings[bind_count++] = b;
         } else {