feat: ST-001–ST-005 foundation — scaffolding, Prisma, schema, seed, env

- ST-001: Next.js 16 + React 19 + TypeScript strict + Tailwind + shadcn/ui + all deps
- ST-002: Prisma v7 setup with better-sqlite3 adapter (local) and pg adapter (cloud)
- ST-003: Full schema migration (users, pbis, stories, sprints, tasks, todos, api_tokens)
- ST-004: Seed with 9 PBIs, ~40 stories, demo user (demo/demo1234), lars user
- ST-005: Zod-validated env vars, .env.example, lib/session, lib/auth, lib/api-auth

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

actions/auth.ts

@@ -0,0 +1,68 @@
+'use server'
+
+import { redirect } from 'next/navigation'
+import { cookies } from 'next/headers'
+import { getIronSession } from 'iron-session'
+import { z } from 'zod'
+import { registerUser, verifyUser } from '@/lib/auth'
+import { SessionData, sessionOptions } from '@/lib/session'
+
+const registerSchema = z.object({
+  username: z.string().min(3, 'Gebruikersnaam moet minimaal 3 tekens bevatten').max(50),
+  password: z.string().min(8, 'Wachtwoord moet minimaal 8 tekens bevatten'),
+})
+
+const loginSchema = z.object({
+  username: z.string().min(1),
+  password: z.string().min(1),
+})
+
+export async function registerAction(formData: FormData) {
+  const parsed = registerSchema.safeParse({
+    username: formData.get('username'),
+    password: formData.get('password'),
+  })
+
+  if (!parsed.success) {
+    return { error: parsed.error.flatten().fieldErrors }
+  }
+
+  const result = await registerUser(parsed.data.username, parsed.data.password)
+  if (result.error) return { error: result.error }
+
+  const session = await getIronSession<SessionData>(await cookies(), sessionOptions)
+  session.userId = result.user!.id
+  session.isDemo = false
+  await session.save()
+
+  redirect('/dashboard')
+}
+
+export async function loginAction(formData: FormData) {
+  const parsed = loginSchema.safeParse({
+    username: formData.get('username'),
+    password: formData.get('password'),
+  })
+
+  if (!parsed.success) {
+    return { error: 'Ongeldige inloggegevens' }
+  }
+
+  const user = await verifyUser(parsed.data.username, parsed.data.password)
+  if (!user) {
+    return { error: 'Onjuiste gebruikersnaam of wachtwoord' }
+  }
+
+  const session = await getIronSession<SessionData>(await cookies(), sessionOptions)
+  session.userId = user.id
+  session.isDemo = user.is_demo
+  await session.save()
+
+  redirect('/dashboard')
+}
+
+export async function logoutAction() {
+  const session = await getIronSession<SessionData>(await cookies(), sessionOptions)
+  session.destroy()
+  redirect('/login')
+}