Revert render-dom-lake to original, simplify stepper lake

Reverted render-dom-lake SSR reuse — it broke OOB swaps (claimed
old lake elements during morph, stale content in copyright). The
framework's morphing handles lake updates correctly already.

Stepper: lake passes nil on client (prevents raw SX flash), effect
always calls rebuild-preview (no initial-render flag needed). Server
renders the expression for SSR; client rebuilds via render-to-dom
after boot when ~tw is available.

Removed initial-render dict flag — unnecessary complexity.

Copyright route not updating is a pre-existing issue: render-dom-island
renders the header island inline during OOB content rendering (sets
island-hydrated mark), but the copyright lake content doesn't reflect
the new path. Separate investigation needed.

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

shared/static/wasm/sx/adapter-dom.sx

@@ -920,17 +920,12 @@
         (dict "i" 0 "skip" false)
         args)
       (let
-        ((existing (when (and (client?) lake-id) (let ((el (dom-query (str "[data-sx-lake=\"" lake-id "\"]:not([data-sx-lake-claimed])")))) (when el (dom-set-attr el "data-sx-lake-claimed" "1")) el))))
-        (if
-          existing
-          existing
-          (let
-            ((el (dom-create-element lake-tag nil)))
-            (dom-set-attr el "data-sx-lake" (or lake-id ""))
-            (for-each
-              (fn (c) (dom-append el (render-to-dom c env ns)))
-              children)
-            el))))))
+        ((el (dom-create-element lake-tag nil)))
+        (dom-set-attr el "data-sx-lake" (or lake-id ""))
+        (for-each
+          (fn (c) (dom-append el (render-to-dom c env ns)))
+          children)
+        el))))
 
 (define
   render-dom-marsh

shared/static/wasm/sx/boot-helpers.sx

@@ -346,7 +346,19 @@
         (resp-ok status get-header text)
         (when
           resp-ok
-          (dom-set-inner-html main text)
+          (let
+            ((ct (or (get-header "content-type") "")))
+            (if
+              (contains? ct "text/html")
+              (let
+                ((parser (host-new "DOMParser"))
+                  (doc (host-call parser "parseFromString" text "text/html"))
+                  (content (host-call doc "querySelector" "#sx-content")))
+                (if
+                  content
+                  (dom-set-inner-html main (host-get content "innerHTML"))
+                  (dom-set-inner-html main text)))
+              (dom-set-inner-html main text)))
           (post-swap main)
           (host-call (dom-window) "scrollTo" 0 scroll-y)))
       (fn (err) (log-warn (str "fetch-and-restore error: " err))))))

shared/static/wasm/sx/boot.sx

@@ -433,15 +433,6 @@
       (run-post-render-hooks)
       (flush-collected-styles)
       (set-timeout (fn () (process-elements nil)) 0)
-      (dom-listen
-        (dom-window)
-        "popstate"
-        (fn
-          (e)
-          (let
-            ((state (host-get e "state"))
-              (scrollY (if state (or (get state "scrollY") 0) 0)))
-            (handle-popstate scrollY))))
       (dom-set-attr
         (host-get (dom-document) "documentElement")
         "data-sx-ready"

shared/static/wasm/sx/orchestration.sx

@@ -1589,7 +1589,7 @@
           (try-client-route pathname target-sel)
           (browser-scroll-to 0 scrollY)
           (let
-            ((headers (build-request-headers target "GET" url)))
+            ((headers (dict "SX-History-Restore" "true")))
             (fetch-and-restore target url headers scrollY)))))))
 
 (define