Tests: cek-try-seq / htmx / hs-diag / perform-chain + node HS runners

New spec tests: test-cek-try-seq (CEK try/seq), test-htmx (htmx
directive coverage, 292L), test-hs-diag, test-perform-chain (IO
suspension chains).

tests/hs-*.js: Node.js-side hyperscript runners for browser-mode
testing (hs-behavioral-node, hs-behavioral-runner, hs-parse-audit,
hs-run-timed).

Vendors shared/static/scripts/htmx.min.js.

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

spec/tests/test-cek-try-seq.sx

@@ -0,0 +1,64 @@
+;; Tests for cek-try sequential execution
+;; Bug: hydrate-island fallback leaves hydrating? scope active
+
+(defsuite
+  "cek-try-sequential"
+  (deftest
+    "code after cek-try runs on success"
+    (let
+      ((result (list)))
+      (append! result "before")
+      (cek-try (fn () (append! result "body") 42) (fn (e) nil))
+      (append! result "after")
+      (assert= 3 (len result))
+      (assert= "after" (nth result 2))))
+  (deftest
+    "code after cek-try runs on error"
+    (let
+      ((result (list)))
+      (append! result "before")
+      (cek-try (fn () (error "boom")) (fn (e) (append! result "caught")))
+      (append! result "after")
+      (assert= 3 (len result))
+      (assert= "after" (nth result 2))))
+  (deftest
+    "error in error handler propagates — skips post-try code"
+    (let
+      ((result (list)))
+      (append! result "before")
+      (guard
+        (outer-err (true (append! result "outer-caught")))
+        (cek-try (fn () (error "boom")) (fn (e) (error "handler-boom")))
+        (append! result "after-try"))
+      (assert-true (contains? result "before"))
+      (assert-true (contains? result "outer-caught"))
+      (assert= false (contains? result "after-try"))))
+  (deftest
+    "scope-pop after cek-try executes on error"
+    (scope-push! "test-scope" "value")
+    (cek-try (fn () (error "boom")) (fn (e) nil))
+    (scope-pop! "test-scope")
+    (assert= nil (scope-peek "test-scope")))
+  (deftest
+    "scope-push/pop balanced across cek-try error"
+    (let
+      ((result nil))
+      (scope-push! "bal-test" "pushed")
+      (cek-try (fn () (error "fail")) (fn (e) nil))
+      (set! result (scope-peek "bal-test"))
+      (scope-pop! "bal-test")
+      (assert= "pushed" result)
+      (assert= nil (scope-peek "bal-test"))))
+  (deftest
+    "error handler that errors skips cleanup"
+    (let
+      ((cleaned false))
+      (scope-push! "cleanup-test" "val")
+      (guard
+        (e (true nil))
+        (cek-try (fn () (error "first")) (fn (e) (error "second")))
+        (scope-pop! "cleanup-test")
+        (set! cleaned true))
+      (assert= false cleaned)
+      (assert= "val" (scope-peek "cleanup-test"))
+      (scope-pop! "cleanup-test"))))