Add device access token authentication

backend/prisma/migrations/20260609120000_milestone92_device_access_tokens/migration.sql

@@ -0,0 +1,7 @@
+ALTER TABLE "devices"
+ADD COLUMN "token_hash" TEXT,
+ADD COLUMN "token_created_at" TIMESTAMP(3),
+ADD COLUMN "token_last_used_at" TIMESTAMP(3),
+ADD COLUMN "token_revoked_at" TIMESTAMP(3);
+
+CREATE UNIQUE INDEX "devices_token_hash_key" ON "devices"("token_hash");

backend/prisma/schema.prisma

@@ -31,6 +31,10 @@ model Device {
   deviceName       String            @map("device_name")
   appVersion       String            @map("app_version")
   installTokenHash String            @map("install_token_hash")
+  tokenHash        String?           @unique @map("token_hash")
+  tokenCreatedAt   DateTime?         @map("token_created_at")
+  tokenLastUsedAt  DateTime?         @map("token_last_used_at")
+  tokenRevokedAt   DateTime?         @map("token_revoked_at")
   lastSeenAt       DateTime          @map("last_seen_at")
   createdAt        DateTime          @default(now()) @map("created_at")
   updatedAt        DateTime          @updatedAt @map("updated_at")