Hyperscript conformance: 372→373 — hide/show strategy, generator toEqual

Parser: hide/show handle `with opacity/visibility/display` strategy,
target detection for then-less chaining (add/remove/set/put as boundary).
Generator: inline run().toEqual([...]) pattern for eval-only tests.
Compiler: hide/show emit correct CSS property per strategy.

373/831 (45%)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

spec/tests/test-hyperscript-behavioral.sx

@@ -7731,7 +7731,8 @@
 ;; ── in (1 tests) ──
 (defsuite "hs-upstream-in"
   (deftest "null value in array returns empty"
-    (error "NOT IMPLEMENTED: test HTML could not be parsed into SX"))
+    (assert= (list) (eval-hs "null in [1, 2, 3]"))
+  )
 )
 
 ;; ── logicalOperator (3 tests) ──
@@ -7747,16 +7748,20 @@
 ;; ── mathOperator (5 tests) ──
 (defsuite "hs-upstream-mathOperator"
   (deftest "array + array concats"
-    (error "NOT IMPLEMENTED: test HTML could not be parsed into SX"))
+    (assert= (list 1 2 3 4) (eval-hs "[1, 2] + [3, 4]"))
+  )
   (deftest "array + single value appends"
-    (error "NOT IMPLEMENTED: test HTML could not be parsed into SX"))
+    (assert= (list 1 2 3) (eval-hs "[1, 2] + 3"))
+  )
   (deftest "array + array does not mutate original"
     (assert= (list 1 2) (eval-hs "set a to [1, 2] then set b to a + [3] then return a"))
   )
   (deftest "array concat chains"
-    (error "NOT IMPLEMENTED: test HTML could not be parsed into SX"))
+    (assert= (list 1 2 3) (eval-hs "[1] + [2] + [3]"))
+  )
   (deftest "empty array + array works"
-    (error "NOT IMPLEMENTED: test HTML could not be parsed into SX"))
+    (assert= (list 1 2) (eval-hs "[] + [1, 2]"))
+  )
 )
 
 ;; ── no (5 tests) ──