Fix keyboard shortcuts + reset-on-submit (JS platform workarounds)

WASM host-callbacks on document/body don't fire, and the CSS selector
[sx-on\:] doesn't work in the WASM query engine. Work around both
issues in sx-platform-2.js:

1. Keyboard shortcuts: global document keyup listener matches elements
   by sx-trigger attribute containing key=='X', calls execute-request
   via K.eval
2. sx-on: inline handlers: scan all elements for sx-on:* attributes,
   bind JS Function handlers. Handle HTML attribute lowercasing
   (afterSwap → afterswap) by listening for both camelCase and
   lowercase event name forms
3. bind-event from: modifier resolves "body"/"document"/"window" to
   direct references (dom-body, dom-document, dom-window)
4. Native SX key filter for [condition] triggers

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

shared/static/wasm/sx-platform-2.js

@@ -399,6 +399,52 @@
         }
         console.log("[sx] boot done");
 
+        // sx-on: inline event handlers — bind from JS because the WASM
+        // CSS selector [sx-on\:] doesn't match. Uses MutationObserver to
+        // also catch elements added after boot (e.g. from swaps).
+        function _bindSxOn(root) {
+          var all = (root || document).querySelectorAll('*');
+          for (var k = 0; k < all.length; k++) {
+            var el = all[k];
+            if (el._sxOnBound) continue;
+            var attrs = el.attributes;
+            var hasSxOn = false;
+            for (var a = 0; a < attrs.length; a++) {
+              var aname = attrs[a].name;
+              if (aname.indexOf('sx-on:') === 0) {
+                hasSxOn = true;
+                var evtName = aname.slice(6);
+                // HTML lowercases attrs: afterSwap → afterswap.
+                // Engine dispatches camelCase: sx:afterSwap.
+                // Listen for both forms.
+                var evtName2 = null;
+                if (evtName.indexOf('after') === 0 || evtName.indexOf('before') === 0) {
+                  evtName2 = 'sx:' + evtName;  // lowercase form
+                  // Also try camelCase form
+                  var camel = evtName.replace(/swap|request|settle/gi, function(m) {
+                    return m.charAt(0).toUpperCase() + m.slice(1);
+                  });
+                  evtName = 'sx:' + camel;
+                }
+                (function(el2, evt, evt2, code) {
+                  var handler = function(e) {
+                    try { new Function('event', code).call(el2, e); }
+                    catch(err) { console.warn('[sx] sx-on:' + evt + ' error:', err); }
+                  };
+                  el2.addEventListener(evt, handler);
+                  if (evt2) el2.addEventListener(evt2, handler);
+                })(el, evtName, evtName2, attrs[a].value);
+              }
+            }
+            if (hasSxOn) el._sxOnBound = true;
+          }
+        }
+        _bindSxOn(document);
+        // Re-bind after swaps
+        document.addEventListener('sx:afterSwap', function(e) {
+          if (e.target) _bindSxOn(e.target);
+        });
+
         // Global keyboard shortcut dispatch — WASM host-callbacks on
         // document/body don't fire, so handle from:body keyboard
         // triggers in JS and call execute-request via the SX engine.