Fix aser server-affinity expansion: keyword values, OOB wrapper, page helpers

Three bugs in aser-expand-component (adapter-sx.sx):
- Keyword values were eval'd (eval-expr can't handle <>, HTML tags);
  now asered, matching the aser's rendering capabilities
- Missing default nil binding for unset &key params (caused
  "Undefined symbol" errors for optional params like header-rows)
- aserCall string-quoted keyword values that were already serialized
  SX — now inlines values starting with "(" directly

Server-affinity annotations for layout/nav shells:
- ~shared:layout/app-body, ~shared:layout/oob-sx — page structure
- ~layouts/nav-sibling-row, ~layouts/nav-children — server-side data
- ~layouts/doc already had :affinity :server
- ~cssx/flush marked :affinity :client (browser-only state)

Navigation fix: restore oob_page_sx wrapper for HTMX responses
so #main-panel section exists for sx-select/sx-swap targeting.

OCaml bridge: lazy page helper injection into kernel via IO proxy
(define name (fn (...) (helper "name" ...))) — enables aser_slot
to evaluate highlight/component-source etc. via coroutine bridge.

Playwright tests: added pageerror listener to test_no_console_errors,
new test_navigate_from_home_to_geography for HTMX nav regression.

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

sx/sx/layouts.sx

@@ -57,7 +57,7 @@
 ;; Current section with prev/next siblings.
 ;; 3-column grid: prev is right-aligned, current centered, next left-aligned.
 ;; Current page is larger in the leaf (bottom) row.
-(defcomp ~layouts/nav-sibling-row (&key node siblings is-leaf level depth)
+(defcomp ~layouts/nav-sibling-row (&key node siblings is-leaf level depth) :affinity :server
   (let* ((sibs (or siblings (list)))
          (count (len sibs))
          ;; opacity = (n/x * 3/4) + 1/4
@@ -97,7 +97,7 @@
             (str (get next-node "label") " \u2192")))))))
 
 ;; Children links — shown as clearly clickable buttons.
-(defcomp ~layouts/nav-children (&key items)
+(defcomp ~layouts/nav-children (&key items) :affinity :server
   (div :class "max-w-3xl mx-auto px-4 py-3"
     (div :class "flex flex-wrap justify-center gap-2"
       (map (fn (item)