Add nav seed data and nixserver route modules, update schema/seed

server/prisma/schema.prisma

@@ -427,3 +427,23 @@ model Setting {
 
   @@map("settings")
 }
+
+// ─── Nav Modules ─────────────────────────────────────────────────────────────
+
+model NavModule {
+  id            Int      @id @default(autoincrement())
+  name          String   @unique
+  label         String
+  sectionId     String
+  sectionLabel  String
+  sectionIcon   String   @default("Settings")
+  sectionTo     String?
+  sectionWeight Int      @default(100)
+  weight        Int      @default(100)
+  route         String
+  enabled       Boolean  @default(true)
+  builtIn       Boolean  @default(true)
+  createdAt     DateTime @default(now())
+
+  @@map("nav_modules")
+}