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/adapter-dom.sx

@@ -181,8 +181,7 @@
                     ;; Value must be callable (lambda/function)
                     (and (starts-with? attr-name "on-")
                          (callable? attr-val))
-                      (let ((event-name (substring attr-name 3 (string-length attr-name))))
-                        (dom-listen el event-name attr-val))
+                      (dom-listen el (slice attr-name 3) attr-val)
                     ;; Boolean attr
                     (contains? BOOLEAN_ATTRS attr-name)
                       (when attr-val (dom-set-attr el attr-name ""))