HS: type-check : returns the value (not a bool) — +2 typecheck

`'foo' : String` and `'foo' : String!` were returning `true` because
`hs-type-check` was a predicate. Per upstream hyperscript semantics,
`value : Type` is a type-asserted pass-through:
- nil passes the basic check (use `Type!` for non-null)
- mismatched type → raise "Typecheck failed!"
- match → return the original value

`hs-type-check-strict` now also raises on nil rather than returning
false, so the `String!` form actually rejects null.

hs-upstream-expressions/typecheck: 0/5 → 2/5.
asExpression unchanged (uses different `as Type` runtime path).

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

lib/hyperscript/runtime.sx

@@ -775,25 +775,22 @@
     (value type-name)
     (if
       (nil? value)
-      true
-      (cond
-        ((= type-name "Number") (number? value))
-        ((= type-name "String") (string? value))
-        ((= type-name "Boolean") (or (= value true) (= value false)))
-        ((= type-name "Array") (list? value))
-        ((= type-name "Object") (dict? value))
-        ((= type-name "Element") (= (host-typeof value) "element"))
-        ((= type-name "Node")
-          (or
-            (= (host-typeof value) "element")
-            (= (host-typeof value) "text")))
-        (true (= (host-typeof value) (downcase type-name)))))))
+      value
+      (let
+        ((matches (cond ((= type-name "Number") (number? value)) ((= type-name "String") (string? value)) ((= type-name "Boolean") (or (= value true) (= value false))) ((= type-name "Array") (list? value)) ((= type-name "Object") (dict? value)) ((= type-name "Element") (= (host-typeof value) "element")) ((= type-name "Node") (or (= (host-typeof value) "element") (= (host-typeof value) "text"))) (true (= (host-typeof value) (downcase type-name))))))
+        (if
+          matches
+          value
+          (raise (str "Typecheck failed! expected " type-name)))))))
 
 (define
   hs-type-check-strict
   (fn
     (value type-name)
-    (if (nil? value) false (hs-type-check value type-name))))
+    (if
+      (nil? value)
+      (raise (str "Typecheck failed! expected " type-name " but got nil"))
+      (hs-type-check value type-name))))
 
 (define
   hs-strict-eq