HS: fix empty/halt/morph/reset/dialog — 17 upstream tests pass

- parser `empty` no-target → (ref "me") (was bogus (sym "me"))
- parser `halt` modes distinguish: "all"/"bubbling"/"default" halt execution
  (raise hs-return), "the-event"/"the event's" only stop propagation/default.
  "'s" now matched as op token, not keyword.
- parser `get` cmd: dispatch + cmd-kw list + parse-get-cmd (parses expr with
  optional `as TYPE`). Required for `get result as JSON` in fetch chains.
- compiler empty-target for (local X): emit (set! X (hs-empty-like X)) so
  arrays/sets/maps clear the variable, not call DOM empty on the value.
- runtime hs-empty-like: container-of-same-type empty value.
- runtime hs-empty-target!: drop dead FORM branch that was short-circuiting
  to innerHTML=""; the querySelectorAll-over-inputs branch now runs.
- runtime hs-halt!: take ev param (was free `event` lookup); raise hs-return
  to stop execution unless mode is "the-event".
- runtime hs-reset!: type-aware — FORM → reset, INPUT/TEXTAREA → value/checked
  from defaults, SELECT → defaultSelected option.
- runtime hs-open!/hs-close!: toggle `open` attribute on details elements
  (not just the prop) so dom-has-attr? assertions work.
- runtime hs-coerce JSON: json-stringify dict/list (was str).
- test-runner mock: host-get on List + "length"/"size" (was only Dict);
  dom-set-attr tracks defaultChecked / defaultSelected / defaultValue;
  mock_query_all supports comma-separated selector groups.
- generator: emit boolean attrs (checked/selected/etc) even with null value;
  drop overcautious "skip HS with bare quotes or embedded HTML" guard so
  morph tests (source contains embedded <div>) emit properly.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

shared/static/wasm/sx/hs-tokenizer.sx

@@ -117,6 +117,7 @@
     "first"
     "last"
     "random"
+    "pick"
     "empty"
     "clear"
     "swap"
@@ -173,11 +174,17 @@
     "default"
     "halt"
     "precedes"
+    "precede"
+    "follow"
     "follows"
     "ignoring"
     "case"
+    "changes"
     "focus"
-    "blur"))
+    "blur"
+    "dom"
+    "morph"
+    "using"))
 
 (define hs-keyword? (fn (word) (some (fn (k) (= k word)) hs-keywords)))
 
@@ -472,6 +479,14 @@
                   (hs-advance! 1)
                   (hs-emit! "attr" (read-ident pos) start)
                   (scan!))
+                (and
+                  (= ch "^")
+                  (< (+ pos 1) src-len)
+                  (hs-ident-char? (hs-peek 1)))
+                (do
+                  (hs-advance! 1)
+                  (hs-emit! "hat" (read-ident pos) start)
+                  (scan!))
                 (and
                   (= ch "~")
                   (< (+ pos 1) src-len)