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/design-system/layout/Sidebar/SidebarTree.tsx

@@ -2,6 +2,7 @@ import {
   useState,
   useRef,
   useCallback,
+  useEffect,
   useMemo,
   type ReactNode,
   type KeyboardEvent,
@@ -31,6 +32,7 @@ export interface SidebarTreeProps {
   className?: string
   filterQuery?: string
   persistKey?: string     // sessionStorage key to persist expand state across remounts
+  autoRevealPath?: string | null  // when set, auto-expand the parent of the matching node
 }
 
 // ── Star icon SVGs ───────────────────────────────────────────────────────────
@@ -138,6 +140,7 @@ export function SidebarTree({
   className,
   filterQuery,
   persistKey,
+  autoRevealPath,
 }: SidebarTreeProps) {
   const navigate = useNavigate()
 
@@ -146,6 +149,27 @@ export function SidebarTree({
     () => persistKey ? readExpandState(persistKey) : new Set(),
   )
 
+  // Auto-expand parent when autoRevealPath changes (e.g. from Cmd-K navigation)
+  useEffect(() => {
+    if (!autoRevealPath) return
+    for (const node of nodes) {
+      // Check if a child of this node matches the reveal path
+      if (node.children?.some((child) => child.path === autoRevealPath)) {
+        if (!userExpandedIds.has(node.id)) {
+          setUserExpandedIds((prev) => {
+            const next = new Set(prev)
+            next.add(node.id)
+            if (persistKey) writeExpandState(persistKey, next)
+            return next
+          })
+        }
+        break
+      }
+      // Also check if the node itself matches (top-level node, no parent to expand)
+      if (node.path === autoRevealPath) break
+    }
+  }, [autoRevealPath]) // eslint-disable-line react-hooks/exhaustive-deps
+
   // Filter
   const { filtered, matchedParentIds } = useMemo(
     () => filterNodes(nodes, filterQuery ?? ''),