fix(agent-team): address UI review (column flex height, ARIA, token consistency)

Fresh-context deep review verdict was SHIP-WITH-FIXES (all hard constraints held:
read-only, inert gate panel, XSS posture, no backend, gate-vs-inert semantics).
Resolved:
- Board columns: replace magic calc(100vh-220px) ScrollArea cap with a proper
  flex chain (h-full/min-h-0) so card lists size to real column height at any
  window size / wrapped toolbar.
- Valid ARIA: stage row is role=list, each column a role=listitem wrapping a
  role=listbox of task-card options (no malformed listbox nesting).
- TopBar health dot uses status-active/status-failed tokens (no hardcoded Tailwind
  palette colors).
- Stale TaskList reference in badge.tsx comment.

Typecheck + 36 tests + build all green.

agent-team/web/src/components/Board.tsx

@@ -187,12 +187,12 @@ export function Board({
         )}
       </div>
 
-      {/* Kanban columns — horizontal scroll */}
+      {/* Kanban columns — horizontal scroll. Each column is its own listbox of
+          task cards (valid ARIA nesting), so this row is just a labelled list. */}
       <div
         className="flex gap-3 overflow-x-auto pb-2 flex-1 min-h-0 px-1"
-        role="listbox"
+        role="list"
         aria-label="pipeline stages"
-        aria-multiselectable="false"
       >
         {filteredStages.map((stage) => (
           <KanbanColumn
@@ -229,9 +229,10 @@ function KanbanColumn({ stage, topology, selectedId, onSelect }: ColumnProps) {
   return (
     <div
       className={cn(
-        "flex flex-col gap-1.5 w-52 shrink-0 rounded-lg bg-muted/40 border border-border p-2",
+        "flex h-full min-h-0 w-52 shrink-0 flex-col gap-1.5 rounded-lg border border-border bg-muted/40 p-2",
         inert && "opacity-60",
       )}
+      role="listitem"
       aria-label={`Stage: ${stage.label}`}
     >
       {/* Column header */}
@@ -262,9 +263,14 @@ function KanbanColumn({ stage, topology, selectedId, onSelect }: ColumnProps) {
         </div>
       </div>
 
-      {/* Task cards — scrollable vertically */}
-      <ScrollArea className="flex-1" style={{ maxHeight: "calc(100vh - 220px)" }}>
-        <div className="flex flex-col gap-1.5 pr-1">
+      {/* Task cards — scrollable vertically. flex-1 + min-h-0 lets the list cap
+          at the real column height (no magic viewport math). */}
+      <ScrollArea className="min-h-0 flex-1">
+        <div
+          className="flex flex-col gap-1.5 pr-1"
+          role="listbox"
+          aria-label={`${stage.label} tasks`}
+        >
           {stage.tasks.length === 0 ? (
             <p className="text-xs text-muted-foreground py-3 text-center">—</p>
           ) : (

agent-team/web/src/components/TopBar.tsx

@@ -112,8 +112,8 @@ export function TopBar({ state, connected, generatedAt }: Props) {
           className={cn(
             "w-2.5 h-2.5 rounded-full",
             connected
-              ? "bg-green-500 shadow-[0_0_6px_2px_rgba(34,197,94,0.45)]"
-              : "bg-red-500",
+              ? "bg-status-active shadow-[0_0_6px_2px_hsl(var(--status-active)/0.45)]"
+              : "bg-status-failed",
           )}
         />
         <span className="text-xs text-muted-foreground tabular-nums">

agent-team/web/src/components/ui/badge.tsx

@@ -35,7 +35,7 @@ function Badge({ className, variant, ...props }: BadgeProps) {
 
 /**
  * Map a backend task status / verdict string to a Badge variant. Centralized so
- * TaskCard, TaskList, and TaskDrawer agree on color.
+ * TaskCard, the Board, and TaskDrawer agree on color.
  */
 export function statusVariant(
   status: string,