Register component-affinity as JS primitive for runtime SX access

Fixes 4 test-eval.sx failures (component affinity tests).
Remaining 24 failures are server-only features (defpage, stream-*)
that don't belong in the browser evaluator.

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 = "2026-03-11T03:51:49Z";
+  var SX_VERSION = "2026-03-11T03:56:09Z";
 
   function isNil(x) { return x === NIL || x === null || x === undefined; }
   function isSxTruthy(x) { return x !== false && !isNil(x); }

shared/sx/ref/bootstrap_js.py

@@ -1170,6 +1170,9 @@ CONTINUATIONS_JS = '''
 
   PRIMITIVES["continuation?"] = function(x) { return x != null && x._continuation === true; };
 
+  // Platform accessors — exposed as primitives so user SX code can call them
+  PRIMITIVES["component-affinity"] = componentAffinity;
+
   var _resetResume = [];
 
   function sfReset(args, env) {