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/AgentHealth/AgentHealth.tsx

@@ -18,6 +18,9 @@ import { MonoText } from '../../design-system/primitives/MonoText/MonoText'
 import { Badge } from '../../design-system/primitives/Badge/Badge'
 import { StatCard } from '../../design-system/primitives/StatCard/StatCard'
 
+// Global filters
+import { useGlobalFilters } from '../../design-system/providers/GlobalFilterProvider'
+
 // Mock data
 import { agents, type AgentHealth as AgentHealthData } from '../../mocks/agents'
 import { SIDEBAR_APPS } from '../../mocks/sidebar'
@@ -117,6 +120,7 @@ function buildBreadcrumb(scope: Scope) {
 export function AgentHealth() {
   const scope = useScope()
   const navigate = useNavigate()
+  const { isInTimeRange } = useGlobalFilters()
 
   // Filter agents by scope
   const filteredAgents = useMemo(() => {
@@ -135,8 +139,8 @@ export function AgentHealth() {
   const totalTps = filteredAgents.reduce((s, a) => s + a.tps, 0)
   const totalActiveRoutes = filteredAgents.reduce((s, a) => s + a.activeRoutes, 0)
 
-  // Events are a global timeline feed — show all regardless of scope
-  const filteredEvents = agentEvents
+  // Filter events by global time range
+  const filteredEvents = agentEvents.filter((e) => isInTimeRange(e.timestamp))
 
   // Single instance for expanded charts
   const singleInstance = scope.level === 'instance' ? filteredAgents[0] : null