feat: unified global search & filter system with Cmd-K navigation

Replace per-page filtering with a single GlobalFilterProvider (time range +
status) consumed by a redesigned TopBar across all pages. Lift CommandPalette
to App level so Cmd-K works globally with filtered results that navigate to
exchanges, routes, agents, and applications. Sidebar auto-reveals and selects
the target entry on Cmd-K navigation via location state.

- Extract shared time preset utilities (computePresetRange, DEFAULT_PRESETS)
- Add GlobalFilterProvider (time range + status) and CommandPaletteProvider
- Add TimeRangeDropdown primitive with Popover preset list
- Redesign TopBar: breadcrumb | time dropdown | status pills | search | env
- Add application category to Cmd-K search
- Remove FilterBar and local DateRangePicker from Dashboard/Metrics pages
- Filter AgentHealth EventFeed by global time range
- Remove shift/onSearchClick props from TopBar

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

src/pages/Metrics/Metrics.module.css

@@ -7,24 +7,12 @@
   background: var(--bg-body);
 }
 
-/* Date range picker bar */
-.dateRangeBar {
-  display: flex;
-  align-items: center;
-  justify-content: space-between;
-  background: var(--bg-surface);
-  border: 1px solid var(--border-subtle);
-  border-radius: var(--radius-md);
-  padding: 10px 16px;
-  margin-bottom: 16px;
-  box-shadow: var(--shadow-card);
-}
-
 .refreshIndicator {
   display: flex;
   align-items: center;
   gap: 6px;
-  flex-shrink: 0;
+  margin-bottom: 12px;
+  justify-content: flex-end;
 }
 
 .refreshDot {

src/pages/Metrics/Metrics.tsx

@@ -1,4 +1,3 @@
-import { useState } from 'react'
 import { useNavigate } from 'react-router-dom'
 import styles from './Metrics.module.css'
 
@@ -16,7 +15,6 @@ import type { Column } from '../../design-system/composites/DataTable/types'
 
 // Primitives
 import { StatCard } from '../../design-system/primitives/StatCard/StatCard'
-import { DateRangePicker } from '../../design-system/primitives/DateRangePicker/DateRangePicker'
 import { Sparkline } from '../../design-system/primitives/Sparkline/Sparkline'
 import { MonoText } from '../../design-system/primitives/MonoText/MonoText'
 import { Badge } from '../../design-system/primitives/Badge/Badge'
@@ -192,10 +190,6 @@ function convertSeries(series: typeof throughputSeries) {
 // ─── Metrics page ─────────────────────────────────────────────────────────────
 export function Metrics() {
   const navigate = useNavigate()
-  const [dateRange, setDateRange] = useState({
-    start: new Date('2026-03-18T06:00:00'),
-    end: new Date('2026-03-18T09:15:00'),
-  })
 
   return (
     <AppShell
@@ -210,20 +204,16 @@ export function Metrics() {
           { label: 'Metrics' },
         ]}
         environment="PRODUCTION"
-        shift="Day (06:00-18:00)"
         user={{ name: 'hendrik' }}
       />
 
       {/* Scrollable content */}
       <div className={styles.content}>
 
-        {/* Date range picker bar */}
-        <div className={styles.dateRangeBar}>
-          <DateRangePicker value={dateRange} onChange={setDateRange} />
-          <div className={styles.refreshIndicator}>
-            <span className={styles.refreshDot} />
-            <span className={styles.refreshText}>Auto-refresh: 30s</span>
-          </div>
+        {/* Auto-refresh indicator */}
+        <div className={styles.refreshIndicator}>
+          <span className={styles.refreshDot} />
+          <span className={styles.refreshText}>Auto-refresh: 30s</span>
         </div>
 
         {/* KPI stat cards (5) */}