feat(ST-510): add TodoCard — aanmaken, bewerken en promoveren

- Aanmaken (+ knop): product-dropdown erft huidige filter, autoFocus op titel
- Bewerken (rij-klik): laadt todo in kaart; velden: product, titel, done-toggle
- Promoveren: → PBI en → Story knoppen openen bestaande dialogs
- key op TodoCard dwingt remount bij ander geselecteerde rij zodat
  defaultValue-velden altijd de juiste todo tonen
- SaveButton via useFormStatus voor pending-state op submit

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

components/todos/todo-list.tsx

@@ -1,6 +1,8 @@
 'use client'
 
 import { useState, useTransition, useMemo, useEffect, useRef, useCallback } from 'react'
+import { useActionState } from 'react'
+import { useFormStatus } from 'react-dom'
 import {
   useReactTable,
   getCoreRowModel,
@@ -18,11 +20,12 @@ import { Input } from '@/components/ui/input'
 import { DemoTooltip } from '@/components/shared/demo-tooltip'
 import { Table, TableBody, TableCell, TableHead, TableHeader, TableRow } from '@/components/ui/table'
 import {
+  createTodoAction,
+  updateTodoAction,
   archiveSelectedTodosAction,
   promoteTodoToPbiAction,
   promoteTodoToStoryAction,
 } from '@/actions/todos'
-import { useActionState } from 'react'
 
 interface Todo {
   id: string
@@ -70,6 +73,15 @@ function IndeterminateCheckbox({
   )
 }
 
+function SaveButton() {
+  const { pending } = useFormStatus()
+  return (
+    <Button type="submit" size="sm" disabled={pending}>
+      {pending ? '…' : 'Opslaan'}
+    </Button>
+  )
+}
+
 // --- Promote to PBI dialog ---
 function PromotePbiDialog({
   todo,
@@ -217,6 +229,141 @@ function PromoteStoryDialog({
   )
 }
 
+// --- Detail card ---
+function TodoCard({
+  mode,
+  activeTodo,
+  products,
+  isDemo,
+  defaultProductId,
+  onSuccess,
+  onPromotePbi,
+  onPromoteStory,
+}: {
+  mode: 'idle' | 'create' | 'edit'
+  activeTodo: Todo | null
+  products: Product[]
+  isDemo: boolean
+  defaultProductId: string
+  onSuccess: () => void
+  onPromotePbi: (todo: Todo) => void
+  onPromoteStory: (todo: Todo) => void
+}) {
+  const [createState, createFormAction] = useActionState(createTodoAction, undefined)
+  const [editState, editFormAction] = useActionState(updateTodoAction, undefined)
+
+  useEffect(() => {
+    if (createState?.success) onSuccess()
+  }, [createState, onSuccess])
+
+  useEffect(() => {
+    if (editState?.success) onSuccess()
+  }, [editState, onSuccess])
+
+  if (mode === 'idle') {
+    return (
+      <div className="rounded-xl border border-border bg-surface-container-low p-5 min-h-[88px] flex items-center justify-center">
+        <p className="text-sm text-muted-foreground">Selecteer een rij of klik op + om te beginnen.</p>
+      </div>
+    )
+  }
+
+  if (mode === 'create') {
+    return (
+      <div className="rounded-xl border border-border bg-surface-container-low p-5">
+        <p className="text-xs font-medium text-muted-foreground uppercase tracking-wide mb-3">Nieuwe todo</p>
+        <form action={createFormAction} className="space-y-3">
+          <div className="flex gap-3">
+            <select
+              name="productId"
+              defaultValue={defaultProductId}
+              disabled={isDemo}
+              className="border border-border rounded-lg px-3 py-1.5 text-sm bg-input-background shrink-0"
+            >
+              <option value="">Geen product</option>
+              {products.map(p => <option key={p.id} value={p.id}>{p.name}</option>)}
+            </select>
+            <Input
+              name="title"
+              placeholder="Titel…"
+              disabled={isDemo}
+              autoFocus
+              className="flex-1"
+              autoComplete="off"
+            />
+          </div>
+          {typeof createState?.error === 'string' && (
+            <p className="text-xs text-error">{createState.error}</p>
+          )}
+          <div className="flex gap-2 justify-end">
+            <Button type="button" variant="ghost" size="sm" onClick={onSuccess}>Annuleren</Button>
+            <SaveButton />
+          </div>
+        </form>
+      </div>
+    )
+  }
+
+  // Edit mode
+  if (!activeTodo) return null
+
+  return (
+    <div className="rounded-xl border border-border bg-surface-container-low p-5">
+      <p className="text-xs font-medium text-muted-foreground uppercase tracking-wide mb-3">Todo bewerken</p>
+      <form action={editFormAction} className="space-y-3">
+        <input type="hidden" name="id" value={activeTodo.id} />
+        <div className="flex gap-3">
+          <select
+            name="productId"
+            defaultValue={activeTodo.product_id ?? ''}
+            disabled={isDemo}
+            className="border border-border rounded-lg px-3 py-1.5 text-sm bg-input-background shrink-0"
+          >
+            <option value="">Geen product</option>
+            {products.map(p => <option key={p.id} value={p.id}>{p.name}</option>)}
+          </select>
+          <Input
+            name="title"
+            defaultValue={activeTodo.title}
+            disabled={isDemo}
+            autoFocus
+            className="flex-1"
+            autoComplete="off"
+          />
+        </div>
+        <label className="flex items-center gap-2 text-sm cursor-pointer w-fit select-none">
+          <input
+            type="checkbox"
+            name="done"
+            defaultChecked={activeTodo.done}
+            disabled={isDemo}
+            className="size-4 accent-primary cursor-pointer"
+          />
+          Afgerond
+        </label>
+        {typeof editState?.error === 'string' && (
+          <p className="text-xs text-error">{editState.error}</p>
+        )}
+        <div className="flex items-center gap-2">
+          {!isDemo && (
+            <>
+              <Button type="button" variant="outline" size="sm" onClick={() => onPromotePbi(activeTodo)}>
+                → PBI
+              </Button>
+              <Button type="button" variant="outline" size="sm" onClick={() => onPromoteStory(activeTodo)}>
+                → Story
+              </Button>
+            </>
+          )}
+          <div className="flex-1" />
+          <Button type="button" variant="ghost" size="sm" onClick={onSuccess}>Annuleren</Button>
+          <SaveButton />
+        </div>
+      </form>
+    </div>
+  )
+}
+
 // --- Main component ---
 export function TodoList({ todos, products, isDemo }: TodoListProps) {
   const [isPending, startTransition] = useTransition()
@@ -307,7 +454,15 @@ export function TodoList({ todos, products, isDemo }: TodoListProps) {
   const totalRows = filtered.length
   const start = totalRows === 0 ? 0 : pageIndex * pageSize + 1
   const end = Math.min((pageIndex + 1) * pageSize, totalRows)
+
   const activeTodo = todos.find(t => t.id === activeRowId) ?? null
+  const cardMode = mode === 'create' ? 'create' : activeTodo ? 'edit' : 'idle'
+  const defaultProductId = selectedProductId !== 'all' ? selectedProductId : ''
+
+  const handleCancel = useCallback(() => {
+    setActiveRowId(null)
+    setMode('idle')
+  }, [])
 
   function handleRowClick(todo: Todo) {
     setActiveRowId(prev => prev === todo.id ? null : todo.id)
@@ -331,6 +486,7 @@ export function TodoList({ todos, products, isDemo }: TodoListProps) {
         toast.success(`${n} todo${n === 1 ? '' : "'s"} gearchiveerd`)
         setRowSelection({})
         setActiveRowId(null)
+        setMode('idle')
       }
     })
   }
@@ -422,16 +578,18 @@ export function TodoList({ todos, products, isDemo }: TodoListProps) {
         </div>
       )}
 
-      {/* Detail card — ST-510 */}
-      <div className="rounded-xl border border-border bg-surface-container-low p-5 min-h-[88px] flex items-center">
-        <p className="text-sm text-muted-foreground">
-          {mode === 'create'
-            ? 'Nieuwe todo aanmaken — kaart wordt gebouwd in ST-510.'
-            : activeTodo
-            ? `Geselecteerd: ${activeTodo.title}`
-            : 'Selecteer een rij of klik op + om te beginnen.'}
-        </p>
-      </div>
+      {/* Detail card */}
+      <TodoCard
+        key={activeRowId ?? (mode === 'create' ? 'create' : 'idle')}
+        mode={cardMode}
+        activeTodo={activeTodo}
+        products={products}
+        isDemo={isDemo}
+        defaultProductId={defaultProductId}
+        onSuccess={handleCancel}
+        onPromotePbi={setPromotePbi}
+        onPromoteStory={setPromoteStory}
+      />
 
       {promotePbi && (
         <PromotePbiDialog todo={promotePbi} products={products} onClose={() => setPromotePbi(null)} />