Portal: add nullable System Name to LicenseKey with per-account unique index

Adds systemName (as typed, trimmed) and systemNameLower (case-folded) to
LicenseKey plus a unique index on (userId, systemNameLower) so names are
case-insensitively unique per account when non-null. Additive and
reversible; migration tested up/down. Regenerates the Prisma client.

prisma/migrations/20260929120000_add_license_key_system_name/migration.sql

@@ -0,0 +1,6 @@
+-- AlterTable
+ALTER TABLE "LicenseKey" ADD COLUMN     "systemName" TEXT,
+ADD COLUMN     "systemNameLower" TEXT;
+
+-- CreateIndex
+CREATE UNIQUE INDEX "LicenseKey_userId_systemNameLower_key" ON "LicenseKey"("userId", "systemNameLower");

prisma/schema.prisma

@@ -205,10 +205,17 @@ model LicenseKey {
   userId          String?
   user            User?     @relation(fields: [userId], references: [id], onDelete: SetNull)
   email           String?
+  // Human-readable label set only by the Kiosk (e.g. "Living Room"). Trimmed,
+  // 1-40 chars. Never a reference or foreign key; the License Key is the only
+  // identifier. `systemNameLower` is a case-folded copy used to enforce
+  // per-account, case-insensitive uniqueness when non-null.
+  systemName      String?
+  systemNameLower String?
   // Legacy subscription level. Retained in the database but unmanaged; hidden
   // from the client and left NULL.
   level           String?   @ignore
 
+  @@unique([userId, systemNameLower])
   @@index([userId])
   @@index([email])
 }