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/components/ai-builder/GeneratingAnimation.tsx

@@ -1,33 +1,24 @@
-import { useEffect, useState } from 'react'
-import { Sparkles } from 'lucide-react'
-
-const MESSAGES = [
-  'Analyzing your flow requirements...',
-  'Building decision paths...',
-  'Generating troubleshooting logic...',
-  'Crafting resolution steps...',
-  'Structuring the flow...',
-]
-
-export function GeneratingAnimation() {
-  const [messageIndex, setMessageIndex] = useState(0)
-
-  useEffect(() => {
-    const interval = setInterval(() => {
-      setMessageIndex((prev) => (prev + 1) % MESSAGES.length)
-    }, 3000)
-    return () => clearInterval(interval)
-  }, [])
+interface GeneratingAnimationProps {
+  branchContext?: { current: number; total: number }
+}
 
+export function GeneratingAnimation({ branchContext }: GeneratingAnimationProps) {
   return (
-    <div className="flex flex-col items-center justify-center gap-4 py-12">
-      <div className="relative">
-        <div className="h-12 w-12 animate-spin rounded-full border-4 border-border border-t-primary" />
-        <Sparkles className="absolute left-1/2 top-1/2 h-5 w-5 -translate-x-1/2 -translate-y-1/2 text-primary" />
-      </div>
-      <p className="text-sm text-muted-foreground animate-pulse">
-        {MESSAGES[messageIndex]}
-      </p>
+    <div className="flex flex-col items-center justify-center gap-4 py-10">
+      {/* Spinner */}
+      <div className="h-8 w-8 animate-spin rounded-full border-2 border-border border-t-primary" />
+
+      {/* Branch context (Generate All mode) */}
+      {branchContext ? (
+        <>
+          <p className="text-xs font-label uppercase tracking-wide text-muted-foreground">
+            Branch {branchContext.current} of {branchContext.total}
+          </p>
+          <p className="text-sm text-muted-foreground">Generating branch detail...</p>
+        </>
+      ) : (
+        <p className="text-sm text-muted-foreground">Generating...</p>
+      )}
     </div>
   )
 }