Add Bootstrappers section, essays index, specs prose, layout fixes

- New Bootstrappers top-level section with overview index and JS bootstrapper
  page that runs bootstrap_js.py and displays both source and generated output
  with live script injection (full page load, not SX navigation)
- Essays section: index page with linked cards and summaries, sx-sucks moved
  to end of nav, removed "grand tradition" line
- Specs: English prose descriptions alongside all canonical .sx specs, added
  Boot/CSSX/Browser spec files to architecture page
- Layout: menu bar nav items wrap instead of overflow, baseline alignment
  between label and nav options
- Homepage: added copyright line

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

sx/sxc/home.sx

@@ -4,8 +4,10 @@
   (div :class "max-w-4xl mx-auto px-6 py-16 text-center"
     (h1 :class "text-5xl font-bold text-stone-900 mb-4"
       (span :class "text-violet-600 font-mono" "(<sx>)"))
-    (p :class "text-2xl text-stone-600 mb-8"
+    (p :class "text-2xl text-stone-600 mb-4"
       "s-expressions for the web")
+    (p :class "text-sm text-stone-400"
+      "\u00a9 Giles Bradshaw 2026")
     (p :class "text-lg text-stone-500 max-w-2xl mx-auto mb-12"
       "A hypermedia-driven UI engine that combines htmx's server-first philosophy "
       "with React's component model. S-expressions over the wire — no HTML, no JavaScript frameworks.")