ui: "→ Idee" promote button in TodoCard + PromoteIdeaDialog (M12 T-514)

components/todos/todo-list.tsx:
- TodoCard: new "→ Idee" button next to "→ PBI" + "→ Story" (only shown
  for non-demo)
- PromoteIdeaDialog: confirmation modal — no extra inputs needed since
  promoteTodoToIdeaAction takes only todoId; title/description carry
  over from the todo, status starts as DRAFT
- onPromoteIdea callback wired through TodoCard props
- On success: navigates to /ideas/{new-id} so user lands on the fresh
  idea-detail page

Tests: 546/546 still green.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

components/todos/todo-list.tsx

@@ -3,6 +3,7 @@
 import { useState, useTransition, useMemo, useEffect, useRef, useCallback } from 'react'
 import { useActionState } from 'react'
 import { useFormStatus } from 'react-dom'
+import { useRouter } from 'next/navigation'
 import {
   useReactTable,
   getCoreRowModel,
@@ -26,6 +27,7 @@ import {
   archiveSelectedTodosAction,
   promoteTodoToPbiAction,
   promoteTodoToStoryAction,
+  promoteTodoToIdeaAction,
 } from '@/actions/todos'
 
 interface Todo {
@@ -233,6 +235,60 @@ function PromoteStoryDialog({
   )
 }
 
+// --- Promote to Idea dialog (M12 T-514) ---
+// Geen extra inputs nodig — title/description komen uit de todo, en
+// promoteTodoToIdeaAction archiveert de todo automatisch.
+function PromoteIdeaDialog({
+  todo,
+  onClose,
+}: { todo: Todo; onClose: () => void }) {
+  const router = useRouter()
+  const handleKey = useCallback((e: KeyboardEvent) => { if (e.key === 'Escape') onClose() }, [onClose])
+  useEffect(() => {
+    document.addEventListener('keydown', handleKey)
+    return () => document.removeEventListener('keydown', handleKey)
+  }, [handleKey])
+
+  const [pending, startTransition] = useTransition()
+
+  function handleConfirm() {
+    startTransition(async () => {
+      const r = await promoteTodoToIdeaAction(todo.id)
+      if ('error' in r) {
+        toast.error(r.error)
+        return
+      }
+      toast.success(`Idee aangemaakt (${r.idea_code})`)
+      onClose()
+      router.push(`/ideas/${r.idea_id}`)
+    })
+  }
+
+  return (
+    <div className="fixed inset-0 z-50 flex items-center justify-center bg-black/40">
+      <div className="bg-popover border border-border rounded-xl p-6 w-full max-w-md shadow-xl space-y-4">
+        <h2 className="font-medium text-foreground">Promoveer naar Idee</h2>
+        <p className="text-sm text-muted-foreground">
+          Maak een nieuw idee van &lsquo;<strong>{todo.title}</strong>&rsquo;. De Todo wordt
+          gearchiveerd; je kunt hem later terugvinden in de archief-filter.
+        </p>
+        <p className="text-xs text-muted-foreground">
+          Het idee start als <code>DRAFT</code>. Je kunt het daarna grillen, plannen, en
+          materialiseren tot een PBI.
+        </p>
+        <div className="flex gap-2 justify-end pt-2">
+          <Button type="button" variant="ghost" onClick={onClose} disabled={pending}>
+            Annuleren
+          </Button>
+          <Button onClick={handleConfirm} disabled={pending}>
+            {pending ? 'Bezig…' : 'Promoveren'}
+          </Button>
+        </div>
+      </div>
+    </div>
+  )
+}
+
 // --- Detail card ---
 function TodoCard({
   mode,
@@ -243,6 +299,7 @@ function TodoCard({
   onSuccess,
   onPromotePbi,
   onPromoteStory,
+  onPromoteIdea,
 }: {
   mode: 'idle' | 'create' | 'edit'
   activeTodo: Todo | null
@@ -252,6 +309,7 @@ function TodoCard({
   onSuccess: () => void
   onPromotePbi: (todo: Todo) => void
   onPromoteStory: (todo: Todo) => void
+  onPromoteIdea: (todo: Todo) => void
 }) {
   const [createState, createFormAction] = useActionState(createTodoAction, undefined)
   const [editState, editFormAction] = useActionState(updateTodoAction, undefined)
@@ -366,6 +424,9 @@ function TodoCard({
         <div className="flex items-center gap-2">
           {!isDemo && (
             <>
+              <Button type="button" variant="outline" size="sm" onClick={() => onPromoteIdea(activeTodo)}>
+                → Idee
+              </Button>
               <Button type="button" variant="outline" size="sm" onClick={() => onPromotePbi(activeTodo)}>
                 → PBI
               </Button>
@@ -393,6 +454,7 @@ export function TodoList({ todos, products, isDemo }: TodoListProps) {
   const [mode, setMode] = useState<'idle' | 'create'>('idle')
   const [promotePbi, setPromotePbi] = useState<Todo | null>(null)
   const [promoteStory, setPromoteStory] = useState<Todo | null>(null)
+  const [promoteIdea, setPromoteIdea] = useState<Todo | null>(null)
 
   const filtered = useMemo(() => {
     if (selectedProductId === 'all') return todos
@@ -608,6 +670,7 @@ export function TodoList({ todos, products, isDemo }: TodoListProps) {
         onSuccess={handleCancel}
         onPromotePbi={setPromotePbi}
         onPromoteStory={setPromoteStory}
+        onPromoteIdea={setPromoteIdea}
       />
 
       {promotePbi && (
@@ -616,6 +679,9 @@ export function TodoList({ todos, products, isDemo }: TodoListProps) {
       {promoteStory && (
         <PromoteStoryDialog todo={promoteStory} products={products} onClose={() => setPromoteStory(null)} />
       )}
+      {promoteIdea && (
+        <PromoteIdeaDialog todo={promoteIdea} onClose={() => setPromoteIdea(null)} />
+      )}
     </div>
   )
 }