Fix island hydration double-render bug, add marshes plan

Client-rendered islands were re-hydrated by boot.sx because
renderDomIsland didn't mark them as processed. Hydration read
empty data-sx-state, overwriting kwargs (e.g. path) with NIL.
Fix: mark-processed! in adapter-dom.sx so boot skips them.

New plan: marshes — where reactivity and hypermedia interpenetrate.
Three patterns: server writes to signals, reactive marsh zones with
transforms, and signal-bound hypermedia interpretation.

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

shared/static/scripts/sx-browser.js

@@ -14,7 +14,7 @@
   // =========================================================================
 
   var NIL = Object.freeze({ _nil: true, toString: function() { return "nil"; } });
-  var SX_VERSION = "2026-03-10T14:25:47Z";
+  var SX_VERSION = "2026-03-10T15:52:32Z";
 
   function isNil(x) { return x === NIL || x === null || x === undefined; }
   function isSxTruthy(x) { return x !== false && !isNil(x); }
@@ -1781,6 +1781,7 @@ return result; }, args);
   var container = domCreateElement("span", NIL);
   var disposers = [];
   domSetAttr(container, "data-sx-island", islandName);
+  markProcessed(container, "island-hydrated");
   return (function() {
   var bodyDom = withIslandScope(function(disposable) { return append_b(disposers, disposable); }, function() { return renderToDom(componentBody(island), local, ns); });
   domAppend(container, bodyDom);