refactor(fe): DRY components, hooks, a11y fixes, and WS/client improvements

- Extract StatusBadge, SummaryList, ProfileDetail shared components (~300 lines deduplicated)
- Extract usePaginatedList<T>, useItemDetail<T> generic hooks (~170 lines deduplicated)
- Fix a11y: Badge (role=status, dark variants), Button (aria-disabled, motion-safe), Input (aria-invalid, errorId), Select (error variant), Skeleton (aria-hidden), MobileTabBar (full tab ARIA), Toast (timer leak fix, role=alert, keyboard dismiss), Card (role=region)
- Fix API client: buildSearchParams helper, request timeout, password caching, named types
- Fix WS: typed 24 event payloads (was all unknown), exponential backoff reconnect, max 20 attempts, msg.data guard
- Fix bug: listDashboardChannels cursor pagination was silently dropped
- Remove duplicate shimmer keyframes from tailwind.config.js
- Fix WaveformPlayer non-null assertion

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

services/frontend/src/features/dashboard/components/DashboardStats.tsx

@@ -10,6 +10,7 @@ import {
   Users,
 } from "lucide-react";
 import { cardItem, cardStagger } from "../../../shared/hooks/useFramerStagger";
+import { useUIState } from "../../../shared/hooks/useUIState";
 import { cn } from "../../../shared/lib/utils";
 import {
   Card,
@@ -20,7 +21,6 @@ import {
   StatusBadge,
 } from "../../../shared/ui";
 import { useDashboardStats } from "../hooks/useDashboard";
-import { useUIState } from "../../../shared/hooks/useUIState";
 
 export function DashboardStatsContent() {
   const { stats, loading, error, refetch } = useDashboardStats();
@@ -129,7 +129,11 @@ export function DashboardStatsContent() {
         {cards.map((card) => (
           <Card
             key={card.title}
-            className={cn("overflow-hidden", card.onClick && "cursor-pointer transition-colors hover:bg-accent/50")}
+            className={cn(
+              "overflow-hidden",
+              card.onClick &&
+                "cursor-pointer transition-colors hover:bg-accent/50",
+            )}
             onClick={card.onClick}
           >
             <CardContent className="p-4">