feat: AI flow builder, visibility model, dashboard tabs, fork UI (#88)

- AI flow builder: scaffold → branch detail → assemble → review flow
- Generate All one-click branch generation with stop/cancel
- Regenerate scaffold suggestions button
- 3-action review screen: Start Flow, Open in Editor, Build Another
- Fix Publish button gated behind !isDirty
- Fix visibility column enforcement in tree access filter
- Add ?visibility filter and author_name to GET /trees
- Dashboard tabbed flows: My Flows / My Team / Public / All
- Create button in My Flows tab, window focus reload (stale data fix)
- Fork UI with optional reason modal
- Fix account_id nullability in User type and schema
- Keep is_public and visibility in sync on updates

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/pages/TeamAnalyticsPage.tsx

@@ -11,8 +11,10 @@ import {
   ResponsiveContainer,
 } from 'recharts'
 import { Spinner } from '@/components/common/Spinner'
+import { EmptyState } from '@/components/common/EmptyState'
 import { analyticsApi } from '@/api'
 import { usePermissions } from '@/hooks/usePermissions'
+import { toast } from '@/lib/toast'
 import type { TeamAnalyticsResponse, AnalyticsPeriod } from '@/types'
 
 const CHART_COLORS = {
@@ -46,6 +48,12 @@ export default function TeamAnalyticsPage() {
       .finally(() => setLoading(false))
   }, [period, isAccountOwner, isSuperAdmin])
 
+  useEffect(() => {
+    if (!isAccountOwner && !isSuperAdmin) {
+      toast.info('Viewing your personal analytics', { id: 'analytics-redirect' })
+    }
+  }, [isAccountOwner, isSuperAdmin])
+
   if (!isAccountOwner && !isSuperAdmin) {
     return <Navigate to="/analytics/me" replace />
   }
@@ -60,8 +68,11 @@ export default function TeamAnalyticsPage() {
 
   if (!data) {
     return (
-      <div className="flex items-center justify-center min-h-[60vh]">
-        <p className="text-muted-foreground">Failed to load analytics data.</p>
+      <div className="container mx-auto px-4 py-6 sm:px-6 sm:py-8">
+        <EmptyState
+          title="Analytics unavailable"
+          description="Failed to load analytics data. Please try again."
+        />
       </div>
     )
   }