Add event bindings and data-sx-emit processing

- adapter-dom.sx: detect :on-click/:on-submit etc. in render-dom-element
  — if attr starts with "on-" and value is callable, wire via dom-listen
- orchestration.sx: add process-emit-elements for data-sx-emit attrs
  — auto-dispatch custom events on click with optional JSON detail
- bootstrap_js.py: add processEmitElements RENAME
- Regenerate sx-ref.js with all changes
- Update reactive-islands status table

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

shared/sx/ref/adapter-dom.sx

@@ -170,6 +170,12 @@
                     ;; nil or false → skip
                     (or (nil? attr-val) (= attr-val false))
                       nil
+                    ;; Event handler: on-click, on-submit, on-input, etc.
+                    ;; 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))
                     ;; Boolean attr
                     (contains? BOOLEAN_ATTRS attr-name)
                       (when attr-val (dom-set-attr el attr-name ""))
@@ -589,6 +595,11 @@
 ;;   (dom-child-nodes frag)       → list of child nodes
 ;;   (dom-remove-children-after m)→ void (remove all siblings after marker)
 ;;   (dom-set-data el key val)    → void (store arbitrary data on element)
+;;   (dom-get-data el key)        → any (retrieve data stored on element)
+;;
+;; Event handling:
+;;   (dom-listen el name handler) → remove-fn (addEventListener, returns remover)
+;;   (dom-dispatch el name detail)→ boolean (dispatch CustomEvent, bubbles: true)
 ;;
 ;; Content parsing:
 ;;   (dom-parse-html s)           → DocumentFragment from HTML string