Fix reactive islands client-side navigation and hydration

Three bugs prevented islands from working during SX wire navigation:

1. components_for_request() only bundled Component and Macro defs, not
   Island defs — client never received defisland definitions during
   navigation (components_for_page for initial HTML shell was correct).

2. hydrate-island used morph-children which can't transfer addEventListener
   event handlers from freshly rendered DOM to existing nodes. Changed to
   clear+append so reactive DOM with live signal subscriptions is inserted
   directly.

3. asyncRenderToDom (client-side async page eval) checked _component but
   not _island on ~-prefixed names — islands fell through to generic eval
   which failed. Now delegates to renderDomIsland.

4. setInterval_/setTimeout_ passed SX Lambda objects directly to native
   timers. JS coerced them to "[object Object]" and tried to eval as code,
   causing "missing ] after element list". Added _wrapSxFn to convert SX
   lambdas to JS functions before passing to timers.

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

shared/sx/ref/deps.sx

@@ -20,7 +20,6 @@
 ;;   (component-deps c)       → cached deps list (may be empty)
 ;;   (component-set-deps! c d)→ cache deps on component
 ;;   (component-css-classes c)→ pre-scanned CSS class list
-;;   (env-components env)     → list of component/macro names in env
 ;;   (regex-find-all pat src) → list of capture group 1 matches
 ;;   (scan-css-classes src)   → list of CSS class strings from source
 ;; ==========================================================================
@@ -423,7 +422,20 @@
 ;;   (component-set-io-refs! c r)→ cache IO refs on component
 ;;   (component-affinity c)      → "auto" | "client" | "server"
 ;;   (macro-body m)           → AST body of macro
-;;   (env-components env)     → list of component names in env
 ;;   (regex-find-all pat src) → list of capture group matches
 ;;   (scan-css-classes src)   → list of CSS class strings from source
 ;; --------------------------------------------------------------------------
+
+
+;; --------------------------------------------------------------------------
+;; env-components — list component/macro names in an environment
+;; --------------------------------------------------------------------------
+;; Moved from platform to spec: pure logic using type predicates.
+
+(define env-components
+  (fn (env)
+    (filter
+      (fn (k)
+        (let ((v (env-get env k)))
+          (or (component? v) (macro? v))))
+      (keys env))))