HS: DOM ref-eq + compound selector + DOM tree fixes

- hs-id= uses JS === for DOM elements (hs-ref-eq), = for scalars
- != operator now uses hs-id= for structural correctness
- compound tag[attr=val] selector matching in test runner
- dom-query-all replaces host-call querySelectorAll
- DOM tree structure corrected in 4 generated tests (elements were
  appended to wrong parents)

tests/hs-run-filtered.js

@@ -297,6 +297,15 @@ function mt(e,s) {
     const m = base.match(/^\[([^\]=]+)(?:="([^"]*)")?\]$/);
     if(m) return m[2] !== undefined ? e.getAttribute(m[1]) === m[2] : e.hasAttribute(m[1]);
   }
+  // Compound tag[attr=val] e.g. input[type=checkbox] or input[type="checkbox"]
+  if(base.includes('[')) {
+    const cm = base.match(/^([\w-]+)(\[.+\])$/);
+    if(cm) {
+      if(e.tagName.toLowerCase() !== cm[1]) return false;
+      const attrParts = cm[2].match(/^\[([^\]=]+)(?:=["']?([^"'\]]+)["']?)?\]$/);
+      if(attrParts) return attrParts[2] !== undefined ? e.getAttribute(attrParts[1]) === attrParts[2] : e.hasAttribute(attrParts[1]);
+    }
+  }
   if(base.includes('.')) { const [tag, cls] = base.split('.'); return e.tagName.toLowerCase() === tag && e.classList.contains(cls); }
   if(base.includes('#')) { const [tag, id] = base.split('#'); return e.tagName.toLowerCase() === tag && e.id === id; }
   return e.tagName.toLowerCase() === base.toLowerCase();
@@ -536,6 +545,9 @@ globalThis.console = { log: () => {}, error: () => {}, warn: () => {}, info: ()
 const _log = _origLog; // keep reference for our own output
 
 // ─── FFI ────────────────────────────────────────────────────────
+// JS-level reference equality for host objects (works around OCaml boxing).
+// The SX `=` primitive doesn't do JS === for host objects in the WASM kernel.
+K.registerNative('hs-ref-eq',a=>a[0]===a[1]);
 K.registerNative('host-global',a=>{const n=a[0];return(n in globalThis)?globalThis[n]:null;});
 K.registerNative('host-get',a=>{
   if(a[0]==null)return null;