HS: remove parse-cmd callable guard — allow all expression statements (+45 tests)

The callable check added in 0bef67dd rejected legitimate expression
statements (as-conversions, array literals, property access, breakpoint)
because they produce non-call AST nodes. The at-end? guard already handles
the trailing-then EOF case; the callable check is redundant and wrong.
Removing it restores the original open fallback: any parse-expr result is
a valid command. arrayLiteral 8/8, breakpoint 2/2, asExpression +35,
evalStatically +5, regressions +3.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/hyperscript/parser.sx

@@ -2871,18 +2871,7 @@
                       (list (quote view-transition!) using body)))))
               ((and (= typ "keyword") (or (= val "on") (= val "init") (= val "def") (= val "behavior") (= val "live") (= val "when") (= val "bind")))
                 nil)
-              (true
-                (if
-                  (at-end?)
-                  nil
-                  (let
-                    ((expr (parse-expr)))
-                    (let
-                      ((callable? (if (and (dict? expr) (get expr :hs-ast)) (= (get expr :kind) "call") (or (= (first expr) (quote call)) (= (first expr) (quote method-call))))))
-                      (if
-                        (or callable? hs-span-mode)
-                        expr
-                        (error "Invalid command — expected a function call"))))))))))
+              (true (if (at-end?) nil (parse-expr)))))))
       (define
         parse-cmd-list
         (fn