Step 5p6 lazy loading + Step 6b VM transpilation prep

Lazy module loading (Step 5 piece 6 completion):
- Add define-library wrappers + import declarations to 13 source .sx files
- compile-modules.js generates module-manifest.json with dependency graph
- compile-modules.js strips define-library/import before bytecode compilation
  (VM doesn't handle these as special forms)
- sx-platform.js replaces hardcoded 24-file loadWebStack() with manifest-driven
  recursive loader — only downloads modules the page needs
- Result: 12 modules loaded (was 24), zero errors, zero warnings
- Fallback to full load if manifest missing

VM transpilation prep (Step 6b):
- Refactor lib/vm.sx: 20 accessor functions replace raw dict access
- Factor out collect-n-from-stack, collect-n-pairs, pad-n-nils helpers
- bootstrap_vm.py: transpiles 9 VM logic functions to OCaml
- sx_vm_ref.ml: proof that vm.sx transpiles (preamble has stubs)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

shared/static/wasm/sx/dom.sx

@@ -1,3 +1,7 @@
+(define-library (sx dom)
+  (export dom-document dom-window dom-body dom-head dom-create-element create-text-node create-fragment create-comment dom-append dom-prepend dom-insert-before dom-insert-after dom-remove dom-is-active-element? dom-is-input-element? dom-is-child-of? dom-attr-list dom-remove-child dom-replace-child dom-clone dom-query dom-query-all dom-query-by-id dom-closest dom-matches? dom-get-attr dom-set-attr dom-remove-attr dom-has-attr? dom-add-class dom-remove-class dom-has-class? dom-text-content dom-set-text-content dom-inner-html dom-set-inner-html dom-outer-html dom-insert-adjacent-html dom-get-style dom-set-style dom-get-prop dom-set-prop dom-tag-name dom-node-type dom-node-name dom-id dom-parent dom-first-child dom-next-sibling dom-child-list dom-is-fragment? dom-child-nodes dom-remove-children-after dom-focus dom-parse-html dom-listen dom-add-listener dom-dispatch event-detail prevent-default stop-propagation event-modifier-key? element-value error-message dom-get-data dom-set-data dom-append-to-head set-document-title)
+  (begin
+
 (define dom-document (fn () (host-global "document")))
 
 (define dom-window (fn () (host-global "window")))
@@ -414,3 +418,9 @@
 (define
   set-document-title
   (fn (title) (host-set! (dom-document) "title" title)))
+
+
+))
+
+;; Re-export to global env
+(import (sx dom))