Polish: per-route titles and a way to sign out

There was no sign-out control anywhere. Easy to miss when you develop
permanently signed in, and a stranded feeling for anyone on a shared machine.
Clearing the identity provider's session is sufficient — PIG holds no session
of its own — and the auth listener returns to sign-in without a reload. A hard
redirect follows regardless, so a failed provider call cannot leave a
half-signed-out interface.

Every route now sets its own document title. A single static title makes
browser history and a wall of tabs useless: every entry reads "pig" and nobody
can tell the margin view from the pipeline.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

apps/web/src/pages/Margin.tsx

@@ -8,6 +8,7 @@
 import { useQuery } from '@tanstack/react-query';
 import { compactNumber, get, money, moneyExact, percent } from '@/lib/api';
 import { Card, CardContent, CardHeader, CardTitle, EmptyState, Skeleton, Stat } from '@/components/ui';
+import { usePageTitle } from '@/lib/title';
 
 interface MarginReport {
   totals: {
@@ -36,6 +37,7 @@ interface MarginReport {
 }
 
 export function Margin() {
+  usePageTitle('Margin');
   const { data, isLoading } = useQuery({
     queryKey: ['margin'],
     queryFn: () => get<MarginReport>('/api/capacity/margin'),