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/components/shared/BillCard.tsx

@@ -1,7 +1,7 @@
 import Link from "next/link";
 import { TrendingUp, Calendar, User } from "lucide-react";
 import { Bill } from "@/lib/types";
-import { billLabel, cn, formatDate, partyBadgeColor, trendColor } from "@/lib/utils";
+import { billLabel, chamberBadgeColor, cn, formatDate, partyBadgeColor, trendColor } from "@/lib/utils";
 import { FollowButton } from "./FollowButton";
 
 interface BillCardProps {
@@ -22,9 +22,11 @@ export function BillCard({ bill, compact = false }: BillCardProps) {
             <span className="text-xs font-mono font-semibold text-muted-foreground bg-muted px-1.5 py-0.5 rounded">
               {label}
             </span>
-            <span className="text-xs 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>
+            )}
             {tags.map((tag) => (
               <span
                 key={tag}