SX docs: configurable shell, SX-native event handlers, nav fixes

- Configurable page shell (~sx-page-shell kwargs + SX_SHELL app config)
  so each app controls its own assets — sx docs loads only sx-browser.js
- SX-evaluated sx-on:* handlers (eval-expr instead of new Function)
  with DOM primitives registered in PRIMITIVES table
- data-init boot mode for pure SX initialization scripts
- Jiggle animation on links while fetching
- Nav: 3-column grid for centered alignment, is-leaf sizing,
  fix map-indexed param order (index, item), guard mod-by-zero
- Async route eval failure now falls back to server fetch
  instead of silently rendering nothing
- Remove duplicate h1 title from ~doc-page
- Re-bootstrap sx-ref.js + sx-browser.js

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

shared/sx/ref/deps.sx

@@ -308,9 +308,27 @@
       (env-components env))))
 
 
+(define component-io-refs-cached
+  (fn (name env io-names)
+    (let ((key (if (starts-with? name "~") name (str "~" name))))
+      (let ((val (env-get env key)))
+        (if (and (= (type-of val) "component")
+                 (not (nil? (component-io-refs val)))
+                 (not (empty? (component-io-refs val))))
+          (component-io-refs val)
+          ;; Fallback: not yet cached (shouldn't happen after compute-all-io-refs)
+          (transitive-io-refs name env io-names))))))
+
 (define component-pure?
   (fn (name env io-names)
-    (empty? (transitive-io-refs name env io-names))))
+    (let ((key (if (starts-with? name "~") name (str "~" name))))
+      (let ((val (env-get env key)))
+        (if (and (= (type-of val) "component")
+                 (not (nil? (component-io-refs val))))
+          ;; Use cached io-refs (empty list = pure)
+          (empty? (component-io-refs val))
+          ;; Fallback
+          (empty? (transitive-io-refs name env io-names)))))))
 
 
 ;; --------------------------------------------------------------------------
@@ -369,12 +387,12 @@
             (if (= target "server")
               (do
                 (append! server-list name)
-                ;; Collect IO deps from server components
+                ;; Collect IO deps from server components (use cache)
                 (for-each
                   (fn (io-ref)
                     (when (not (contains? io-deps io-ref))
                       (append! io-deps io-ref)))
-                  (transitive-io-refs name env io-names)))
+                  (component-io-refs-cached name env io-names)))
               (append! client-list name))))
         needed)