CUB-121: build React pages with real API integration

- HubPage: agent summary stats, cards, status badges, progress bars, refresh
- LogsPage: activity feed from tasks, status filter, loading skeleton
- ProjectsPage: project cards with status badges and agent counts
- SessionsPage: responsive table/card view with model/token info
- SettingsPage: dark mode toggle, gateway URL, refresh interval persist
- ThemeProvider with dark/light mode via CSS custom properties
- useLocalStorage hook for settings persistence
- Loading/error/empty states across all pages
- npm run build passes cleanly

frontend/src/pages/ProjectsPage.tsx

@@ -1,8 +1,117 @@
+import { useQuery, useQueryClient } from '@tanstack/react-query'
+import { listProjects } from '../services/api'
+import { AlertCircle, RefreshCw, FolderKanban, Users } from 'lucide-react'
+
+const STATUS_COLORS: Record<string, string> = {
+  planned: 'bg-purple-500',
+  active: 'bg-green-500',
+  paused: 'bg-yellow-500',
+  completed: 'bg-blue-400',
+}
+
 export default function ProjectsPage() {
+  const queryClient = useQueryClient()
+
+  const { data, isLoading, error } = useQuery({
+    queryKey: ['projects'],
+    queryFn: listProjects,
+  })
+
+  const projects = data?.data ?? []
+
+  if (isLoading) return <ProjectsSkeleton />
+
+  if (error) {
+    return (
+      <div className="flex flex-col items-center justify-center h-96 gap-4">
+        <AlertCircle size={48} className="text-danger" />
+        <p className="text-danger text-lg">Failed to load projects</p>
+        <button
+          onClick={() => queryClient.invalidateQueries({ queryKey: ['projects'] })}
+          className="flex items-center gap-2 px-4 py-2 rounded-lg bg-primary/10 text-primary hover:bg-primary/20 transition-colors"
+        >
+          <RefreshCw size={16} /> Retry
+        </button>
+      </div>
+    )
+  }
+
   return (
-    <div>
-      <h1 className="text-2xl font-bold mb-4">Projects</h1>
-      <p className="text-on-surface-variant">Tracked projects will appear here.</p>
+    <div className="space-y-6">
+      <header>
+        <h1 className="text-2xl font-bold">Projects</h1>
+        <p className="text-on-surface-variant">Tracked projects and initiatives</p>
+      </header>
+
+      {projects.length === 0 ? (
+        <div className="flex flex-col items-center justify-center h-48 gap-3 border border-dashed border-surface-light rounded-xl">
+          <FolderKanban size={40} className="text-on-surface-muted" />
+          <p className="text-on-surface-muted text-lg">No projects tracked</p>
+          <p className="text-on-surface-muted text-sm">Projects synced from Linear will appear here.</p>
+        </div>
+      ) : (
+        <div className="grid grid-cols-1 sm:grid-cols-2 lg:grid-cols-3 gap-4">
+          {projects.map((project) => (
+            <div
+              key={project.id}
+              className="p-5 rounded-xl border border-surface-light bg-surface-dark hover:border-surface-lighter transition-colors flex flex-col"
+            >
+              <div className="flex items-start justify-between mb-3">
+                <FolderKanban size={20} className="text-on-surface-variant shrink-0 mt-0.5" />
+                <ProjectStatusBadge status={project.status} />
+              </div>
+
+              <h3 className="font-semibold mb-1">{project.name}</h3>
+              {project.description && (
+                <p className="text-sm text-on-surface-variant mb-4 line-clamp-2 flex-1">
+                  {project.description}
+                </p>
+              )}
+
+              <div className="flex items-center gap-2 text-xs text-on-surface-muted pt-3 border-t border-surface-light">
+                <Users size={14} />
+                <span>{project.agentIds?.length ?? 0} agent{(project.agentIds?.length ?? 0) !== 1 ? 's' : ''} assigned</span>
+              </div>
+            </div>
+          ))}
+        </div>
+      )}
+    </div>
+  )
+}
+
+function ProjectStatusBadge({ status }: { status: string }) {
+  return (
+    <div className="flex items-center gap-1.5 px-2 py-1 rounded-full bg-surface-light/50">
+      <div className={`w-2 h-2 rounded-full ${STATUS_COLORS[status] ?? 'bg-gray-500'}`} />
+      <span className="text-xs capitalize text-on-surface-variant">{status}</span>
+    </div>
+  )
+}
+
+function ProjectsSkeleton() {
+  return (
+    <div className="space-y-6 animate-pulse">
+      <div>
+        <div className="h-8 w-40 skeleton mb-2" />
+        <div className="h-4 w-56 skeleton" />
+      </div>
+      <div className="grid grid-cols-1 sm:grid-cols-2 lg:grid-cols-3 gap-4">
+        {[...Array(6)].map((_, i) => (
+          <div key={i} className="p-5 rounded-xl border border-surface-light bg-surface-dark">
+            <div className="flex justify-between mb-3">
+              <div className="h-5 w-5 rounded skeleton" />
+              <div className="h-6 w-20 rounded-full skeleton" />
+            </div>
+            <div className="h-5 w-3/4 skeleton mb-2" />
+            <div className="h-4 w-full skeleton mb-2" />
+            <div className="h-4 w-2/3 skeleton mb-4" />
+            <div className="pt-3 border-t border-surface-light">
+              <div className="h-3 w-32 skeleton" />
+            </div>
+          </div>
+        ))}
+      </div>
     </div>
   )
 }