host: revert legacy-editor shims — clean over fancy, 181/181

Pull out the debt that revived the legacy editor: removed kg-compat.sx (uncommitted
bare->namespaced kg-card aliases), the ./blog container mount, the legacy
sx-editor.js + hardcoded asset URLs + ~editor/sx-editor-styles reuse at /new, and
the blog/sx preloads. /new is now a clean minimal form.

Finding that reshapes Phase 5: render-page (5.1) renders STATIC component trees
but is NOT the full evaluator — a component with a data loop ((map fn items) over
(unquote data)) errors 'Not callable: nil'. So clean dynamic component pages + a
native island editor need the aser SSR pipeline (5.2), not just render-page.

Posts still render via per-block guarded render-page; unsupported editor cards
(~kg-md) show placeholders by design (no alias shim). All endpoints 200, boot clean.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

lib/host/conformance.sh

@@ -63,8 +63,6 @@ MODULES=(
   "lib/persist/durable.sx"
   "spec/render.sx"
   "web/adapter-html.sx"
-  "blog/sx/layouts.sx"
-  "blog/sx/editor.sx"
   "lib/dream/types.sx"
   "lib/dream/json.sx"
   "lib/dream/auth.sx"