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>

shared/sx/templates/layout.sx

@@ -71,7 +71,7 @@
             (h1 (or site-title ""))
             (when app-label
               (span :class "text-lg text-white/80 font-normal" app-label))))
-        (nav :class "hidden md:flex gap-4 text-sm ml-2 justify-end items-center flex-0"
+        (nav :class "hidden md:flex flex-wrap gap-4 text-sm ml-2 justify-end items-center flex-0"
           (when nav-tree nav-tree)
           (when auth-menu auth-menu)
           (when nav-panel nav-panel)
@@ -92,7 +92,7 @@
     (<>
       (div :id id
            :sx-swap-oob (if oob "outerHTML" nil)
-           :class (str "flex flex-col items-center md:flex-row justify-center md:justify-between w-full p-1 bg-" c "-" shade)
+           :class (str "flex flex-col items-center md:flex-row md:items-baseline justify-center md:justify-between w-full p-1 bg-" c "-" shade)
         (div :class "relative nav-group"
           (a :href link-href
              :sx-get (if external nil link-href)
@@ -108,7 +108,7 @@
                 (when selected
                   (span :class "text-lg text-white/80 font-normal" selected))))))
         (when nav
-          (nav :class "hidden md:flex gap-4 text-sm ml-2 justify-end items-center flex-0"
+          (nav :class "hidden md:flex flex-wrap gap-4 text-sm ml-2 justify-end items-baseline flex-0"
             nav)))
       (when (and child-id (not oob))
         (div :id child-id :class "flex flex-col w-full items-center"