feat: notification bell in PageHeader + remove wasted top bar row for supervisors

- PageHeader: renders NotificationBell when isAdmin — bell now appears
  on every page that uses PageHeader (leads, contacts, appointments,
  patients, call history, missed calls, call recordings, live monitor,
  team performance, settings)
- app-shell: top bar row only renders for agents (network indicator +
  status toggle). Supervisors no longer see a wasted empty row.
- Call Recordings: TopBar → PageHeader with badge + info icon
- Live Monitor: TopBar → PageHeader with badge + info icon
- Team Performance: TopBar → PageHeader with info icon
- Settings: TopBar → PageHeader with info icon
- Missed Calls: underline tabs → custom pills (consistent with all pages)
- Desktop overlay app-shell synced with same changes

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/pages/team-performance.tsx

@@ -5,7 +5,7 @@ import {
     faUsers, faPhoneVolume, faCalendarCheck, faPhoneMissed,
     faPercent, faTriangleExclamation,
 } from '@fortawesome/pro-duotone-svg-icons';
-import { TopBar } from '@/components/layout/top-bar';
+import { PageHeader } from '@/components/layout/page-header';
 import { Badge } from '@/components/base/badges/badges';
 import { Table } from '@/components/application/table/table';
 import { apiClient } from '@/lib/api-client';
@@ -292,7 +292,7 @@ export const TeamPerformancePage = () => {
     if (loading) {
         return (
             <>
-                <TopBar title="Team Performance" />
+                <PageHeader title="Team Performance" infoText="Aggregated metrics across all agents." />
                 <div className="flex flex-1 items-center justify-center">
                     <p className="text-sm text-tertiary">Loading team performance...</p>
                 </div>
@@ -302,7 +302,7 @@ export const TeamPerformancePage = () => {
 
     return (
         <>
-            <TopBar title="Team Performance" subtitle="Aggregated metrics across all agents" />
+            <PageHeader title="Team Performance" infoText="Aggregated metrics across all agents." />
 
             <div className="flex flex-1 flex-col overflow-y-auto">
                 {/* Section 1: Key Metrics */}