feat(ST-1112): add shared zod schema for task dialog

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

lib/schemas/task.ts

@@ -0,0 +1,12 @@
+import { z } from 'zod'
+import { TaskStatus } from '@prisma/client'
+
+export const taskSchema = z.object({
+  title: z.string().trim().min(1, 'Verplicht').max(120),
+  description: z.string().max(2000).optional(),
+  implementation_plan: z.string().max(10000).optional(),
+  priority: z.number().int().min(1).max(4),
+  status: z.nativeEnum(TaskStatus).optional(),
+})
+
+export type TaskInput = z.infer<typeof taskSchema>