fix(a11y): MemoryInspectorPanel — sanitise bodyId, add aria-controls (#904)

Memory keys can contain characters like [ ] / : . # and spaces that make
invalid HTML id values (breaks CSS selectors and ARIA id-ref lookups).

- Add sanitizeId() helper: replaces non-alphanumeric chars with hyphens,
  collapses consecutive hyphens, strips leading/trailing hyphens
- Compute bodyId = "mem-body-{sanitizeId(entry.key)}" in MemoryEntryRow
- Set id={bodyId} on the expanded body container
- Set aria-controls={bodyId} on the toggle button so AT can navigate
  directly between the button and its controlled panel

Closes #904

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

canvas/src/components/MemoryInspectorPanel.tsx

@@ -27,6 +27,19 @@ interface Props {
 
 // ── Helpers ───────────────────────────────────────────────────────────────────
 
+/**
+ * Sanitise a memory key for use in an HTML id attribute.
+ * HTML IDs must not contain whitespace; many non-alphanumeric characters also
+ * cause selector or ARIA failures. Replace every non-alphanumeric character
+ * with a hyphen, collapse consecutive hyphens, then strip leading/trailing ones.
+ */
+function sanitizeId(key: string): string {
+  return key
+    .replace(/[^a-zA-Z0-9]/g, "-")
+    .replace(/-+/g, "-")
+    .replace(/^-|-$/g, "");
+}
+
 function formatRelativeTime(iso: string): string {
   const diff = Date.now() - new Date(iso).getTime();
   if (diff < 60_000) return `${Math.floor(diff / 1000)}s`;
@@ -280,6 +293,10 @@ function MemoryEntryRow({
   onCancelEdit,
   onDelete,
 }: MemoryEntryRowProps) {
+  // Sanitise the key so the generated id is a valid HTML id (no spaces or
+  // special chars like [ ] / : . # that would break CSS selectors / ARIA).
+  const bodyId = `mem-body-${sanitizeId(entry.key)}`;
+
   return (
     <div className="rounded-lg border border-zinc-800/60 bg-zinc-900/50 overflow-hidden">
       {/* Header row — click to expand/collapse */}
@@ -287,6 +304,7 @@ function MemoryEntryRow({
         className="w-full flex items-center gap-2 px-3 py-2.5 text-left hover:bg-zinc-800/30 transition-colors"
         onClick={onToggle}
         aria-expanded={isExpanded}
+        aria-controls={bodyId}
       >
         <span className="text-[10px] font-mono text-blue-400 truncate flex-1 min-w-0">
           {entry.key}
@@ -304,7 +322,7 @@ function MemoryEntryRow({
 
       {/* Expanded body */}
       {isExpanded && (
-        <div className="border-t border-zinc-800/50 px-3 pb-3 pt-2 space-y-2">
+        <div id={bodyId} className="border-t border-zinc-800/50 px-3 pb-3 pt-2 space-y-2">
           {entry.expires_at && (
             <p className="text-[9px] text-zinc-500">
               Expires: {new Date(entry.expires_at).toLocaleString()}