HS: fix log multi-arg parsing + put! position aliases + sender lookup

- parse-log-cmd now collects comma-separated args: log a, b, c
  previously only consumed the first arg, causing the rest to be
  standalone statement-commands that failed to parse
- compiler log case emits (do (console-log a) (console-log b) ...)
  since console-log is single-arg
- hs-put! accepts before/after/start/end as aliases for the
  beforebegin/afterend/afterbegin/beforeend positions
- hs-sender uses (get detail "sender") — direct SX dict lookup
  instead of host-get round-trip through JS

Fixes "can reference sender in events" test: 8/8 hs-upstream-send

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

lib/hyperscript/parser.sx

@@ -1748,7 +1748,21 @@
                   dtl
                   (list (quote trigger) name dtl tgt)
                   (list (quote trigger) name tgt)))))))
-      (define parse-log-cmd (fn () (list (quote log) (parse-expr))))
+      (define
+        parse-log-cmd
+        (fn
+          ()
+          (define
+            collect-args
+            (fn
+              (acc)
+              (if
+                (= (tp-type) "comma")
+                (do
+                  (adv!)
+                  (collect-args (append acc (list (parse-expr)))))
+                acc)))
+          (cons (quote log) (collect-args (list (parse-expr))))))
       (define
         parse-inc-cmd
         (fn