Add chamber color badges, action history fallback, and task status polling

- Add chamberBadgeColor util: amber/gold for Senate, slate/silver for House
- Apply chamber badge to BillCard and bill detail header
- ActionTimeline: show latest_action_date/text as fallback when full history
  not yet fetched, with note that full history loads in background
- Manual Controls: poll task status every 5s after triggering, show spinning
  indicator while running, task ID prefix, and completion/failure state

Authored-By: Jack Levy

frontend/app/bills/[id]/page.tsx

@@ -9,7 +9,7 @@ import { ActionTimeline } from "@/components/bills/ActionTimeline";
 import { TrendChart } from "@/components/bills/TrendChart";
 import { NewsPanel } from "@/components/bills/NewsPanel";
 import { FollowButton } from "@/components/shared/FollowButton";
-import { billLabel, congressLabel, formatDate, partyBadgeColor, cn } from "@/lib/utils";
+import { billLabel, chamberBadgeColor, congressLabel, formatDate, partyBadgeColor, cn } from "@/lib/utils";
 
 export default function BillDetailPage({ params }: { params: Promise<{ id: string }> }) {
   const { id } = use(params);
@@ -62,7 +62,11 @@ export default function BillDetailPage({ params }: { params: Promise<{ id: strin
             <span className="font-mono text-sm font-semibold text-muted-foreground bg-muted px-2 py-0.5 rounded">
               {label}
             </span>
-            <span className="text-sm text-muted-foreground">{bill.chamber}</span>
+            {bill.chamber && (
+              <span className={cn("text-xs px-1.5 py-0.5 rounded font-medium", chamberBadgeColor(bill.chamber))}>
+                {bill.chamber}
+              </span>
+            )}
             <span className="text-sm text-muted-foreground">{congressLabel(bill.congress_number)}</span>
           </div>
           <h1 className="text-xl font-bold leading-snug">
@@ -132,7 +136,11 @@ export default function BillDetailPage({ params }: { params: Promise<{ id: strin
               )}
             </div>
           )}
-          <ActionTimeline actions={bill.actions} />
+          <ActionTimeline
+            actions={bill.actions}
+            latestActionDate={bill.latest_action_date}
+            latestActionText={bill.latest_action_text}
+          />
         </div>
         <div className="space-y-4">
           <TrendChart data={trendData} />