feat: dashboard Second Brain, essai 7 jours et vérification e-mail

Rendre le dashboard actionnable (inbox, peek, carte mentale), aligner la facturation sur l’essai 7 jours, et bloquer le login e-mail tant que l’adresse n’est pas confirmée.

Co-authored-by: Cursor <cursoragent@cursor.com>

memento-note/lib/billing/trial-constants.ts

@@ -0,0 +1,2 @@
+/** Free trial length on first Pro / Business checkout. Safe for client imports. */
+export const SUBSCRIPTION_TRIAL_DAYS = 7

memento-note/lib/billing/trial-reminder-email.ts

@@ -0,0 +1,55 @@
+import { sendEmail } from '@/lib/mail'
+
+function formatTrialEnd(date: Date, locale: string): string {
+  try {
+    return new Intl.DateTimeFormat(locale, {
+      day: 'numeric',
+      month: 'long',
+      year: 'numeric',
+    }).format(date)
+  } catch {
+    return date.toISOString().slice(0, 10)
+  }
+}
+
+/**
+ * Best-effort reminder ~3 days before Stripe ends a trial.
+ * Failures are logged by the caller; never throw to the webhook.
+ */
+export async function sendTrialEndingReminder(opts: {
+  to: string
+  name?: string | null
+  trialEndsAt: Date
+  billingUrl: string
+  locale?: string
+}): Promise<{ success: boolean; error?: string }> {
+  const locale = opts.locale?.startsWith('fr') ? 'fr' : 'en'
+  const endLabel = formatTrialEnd(opts.trialEndsAt, locale === 'fr' ? 'fr-FR' : 'en-US')
+  const greet = opts.name?.trim() ? opts.name.trim() : locale === 'fr' ? 'Bonjour' : 'Hi'
+
+  const subject =
+    locale === 'fr'
+      ? 'Votre essai Memento se termine bientôt'
+      : 'Your Memento trial is ending soon'
+
+  const html =
+    locale === 'fr'
+      ? `
+        <p>${greet},</p>
+        <p>Votre période d'essai Memento se termine le <strong>${endLabel}</strong>.</p>
+        <p>Après cette date, votre abonnement démarrera automatiquement avec le moyen de paiement enregistré.</p>
+        <p>Pour gérer votre abonnement ou votre carte&nbsp;:</p>
+        <p><a href="${opts.billingUrl}">Ouvrir la facturation</a></p>
+        <p>— L'équipe Memento</p>
+      `
+      : `
+        <p>${greet},</p>
+        <p>Your Memento trial ends on <strong>${endLabel}</strong>.</p>
+        <p>After that date, your subscription will start automatically using the payment method on file.</p>
+        <p>To manage your subscription or card:</p>
+        <p><a href="${opts.billingUrl}">Open billing settings</a></p>
+        <p>— The Memento team</p>
+      `
+
+  return sendEmail({ to: opts.to, subject, html })
+}

memento-note/lib/billing/trial.ts

@@ -0,0 +1,34 @@
+import { prisma } from '@/lib/prisma'
+
+export { SUBSCRIPTION_TRIAL_DAYS } from '@/lib/billing/trial-constants'
+
+/**
+ * Offer a trial only to users who never held a real Stripe subscription.
+ * Users with cus_mock / price_mock leftovers from local tests are still eligible
+ * if they never had a non-mock stripeSubscriptionId.
+ */
+export async function shouldOfferSubscriptionTrial(userId: string): Promise<boolean> {
+  const sub = await prisma.subscription.findUnique({
+    where: { userId },
+    select: {
+      stripeSubscriptionId: true,
+      tier: true,
+      status: true,
+      trialEndsAt: true,
+    },
+  })
+
+  if (!sub) return true
+
+  const stripeSubId = sub.stripeSubscriptionId
+  if (stripeSubId && !stripeSubId.startsWith('sub_mock')) {
+    return false
+  }
+
+  // Already on a paid / trial tier locally without a Stripe id (admin override)
+  if (sub.tier !== 'BASIC' && (sub.status === 'ACTIVE' || sub.status === 'TRIALING')) {
+    return false
+  }
+
+  return true
+}