htmx demos working: activation, fetch, swap, OOB filtering, test runner page

- htmx-boot-subtree! wired into process-elements for auto-activation
- Fixed cond compilation bug in hx-verb-info (Clojure-style flat cond)
- Platform io-fetch upgraded: method/body/headers support, full response dict
- Replaced perform IO ops with browser primitives (set-timeout, browser-confirm, etc)
- SX→HTML rendering in hx-do-swap with OOB section filtering
- hx-collect-params: collects input name/value for all methods
- Handler naming: ex-{slug} convention, removed perform IO dependencies
- Test runner page at (test.(applications.(htmx))) with iframe-based runner
- Header "test" link on every page linking to test URL
- Page file restructure: 285 files moved to URL-matching paths (a/b/c/index.sx)
- page-functions.sx: ~100 component name references updated
- _test added to skip_dirs, test- file prefix convention for test files

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

sx/sx/layouts/header.sx

@@ -53,4 +53,11 @@
             (span
               (~tw :tokens "text-stone-300 text-xs")
               :style "margin-left:0.5em;"
+              (a
+                :href (str "/sx/(test." (slice path 4) ")")
+                :data-sx-no-boost "true"
+                :target "_self"
+                (~tw :tokens "text-violet-400 text-xs hover:text-violet-600")
+                :style "text-decoration:none;margin-right:0.4em;"
+                "test")
               (str "· " path))))))))