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/prisma/migrations/20260719120000_backfill_email_verified_password_users/migration.sql

@@ -0,0 +1,6 @@
+-- Grandfather existing password accounts so email-verification only applies to new signups.
+-- Non-destructive: only fills NULL emailVerified for users that already have a password.
+UPDATE "User"
+SET "emailVerified" = COALESCE("emailVerified", "createdAt")
+WHERE "password" IS NOT NULL
+  AND "emailVerified" IS NULL;