Add header and event detail pages, fix copyright, rename essay

- Detail pages for all 18 HTTP headers with descriptions, example usage,
  direction badges (request/response/both), and live demos for SX-Prompt,
  SX-Trigger, SX-Retarget
- Detail pages for all 10 DOM events with descriptions, example usage,
  and live demos for beforeRequest, afterSettle, responseError,
  validationFailed
- Header and event table rows now link to their detail pages
- Fix copyright symbol on home page (was literal \u00a9, now actual ©)
- Rename "Godel, Escher, Bach" essay to "Strange Loops" with updated summary
- Remove duplicate script injection from bootstrapper page

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

sx/sxc/home.sx

@@ -7,7 +7,7 @@
     (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")
+      "© 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.")