HS: as Date/Set/Map return real JS host objects (+4 tests)

- hs-coerce "Date": new case returns (host-new "Date" value)
- hs-coerce "Set": creates real JS Set via host-new + for-each add (was SX list)
- hs-coerce "Map": creates real JS Map via host-new + for-each set (was SX list)
- hs-make "Set"/"Map": use host-new instead of (list)/(dict)
- hs-add-to!, hs-remove-from!, hs-empty-like, hs-append: handle real JS Sets
- hs-run-filtered.js: add hs-is-set? and hs-is-map? natives
- generator: MANUAL_TEST_BODIES for converts-as-Date (×2), as-Set, as-Map
asExpression suite: 36/42 (was 32/42)

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

lib/hyperscript/runtime.sx

@@ -470,6 +470,7 @@
           (some (fn (x) (= x value)) target)
           target
           (append target (list value))))
+      ((hs-is-set? target) (do (host-call target "add" value) target))
       (true (do (host-call target "push" value) target)))))
 
 ;; ── Object creation ─────────────────────────────────────────────
@@ -480,10 +481,10 @@
   hs-remove-from!
   (fn
     (value target)
-    (if
-      (list? target)
-      (filter (fn (x) (not (= x value))) target)
-      (host-call target "splice" (host-call target "indexOf" value) 1))))
+    (cond
+      ((list? target) (filter (fn (x) (not (= x value))) target))
+      ((hs-is-set? target) (do (host-call target "delete" value) target))
+      (true (host-call target "splice" (host-call target "indexOf" value) 1)))))
 
 ;; ── Behavior installation ───────────────────────────────────────
 
@@ -965,6 +966,7 @@
             (some (fn (x) (= x value)) target)
             target
             (append target (list value))))
+        ((hs-is-set? target) (do (host-call target "add" value) target))
         ((hs-element? target)
           (do
             (dom-insert-adjacent-html
@@ -1260,22 +1262,24 @@
             value)
           value))
       ((= type-name "Set")
-        (if
-          (list? value)
-          (reduce
-            (fn
-              (acc x)
-              (if (some (fn (a) (= a x)) acc) acc (append acc (list x))))
-            (list)
-            value)
-          value))
+        (let
+          ((s (host-new "Set")))
+          (do
+            (when
+              (list? value)
+              (for-each (fn (x) (host-call s "add" x)) value))
+            s)))
       ((= type-name "Map")
-        (if
-          (dict? value)
-          (let
-            ((ks (if (dict-has? value "_order") (get value "_order") (filter (fn (k) (not (= k "_order"))) (keys value)))))
-            (map (fn (k) (list k (get value k))) ks))
-          value))
+        (let
+          ((m (host-new "Map")))
+          (do
+            (when
+              (dict? value)
+              (for-each
+                (fn (k) (host-call m "set" k (get value k)))
+                (filter (fn (k) (not (= k "_order"))) (keys value))))
+            m)))
+      ((= type-name "Date") (host-new "Date" value))
       (true value))))
 
 (define
@@ -1471,8 +1475,8 @@
             (cond
               ((= type-name "Object") (dict))
               ((= type-name "Array") (list))
-              ((= type-name "Set") (list))
-              ((= type-name "Map") (dict))
+              ((= type-name "Set") (host-new "Set"))
+              ((= type-name "Map") (host-new "Map"))
               (true (dict)))
             (apply host-new (cons type-name args)))))))
   (define
@@ -1871,6 +1875,8 @@
     (cond
       ((list? v) (list))
       ((dict? v) (dict))
+      ((hs-is-set? v) (host-new "Set"))
+      ((hs-is-map? v) (host-new "Map"))
       ((string? v) "")
       ((nil? v) nil)
       (true v))))