feat: implement secure multi-tenancy, RBAC, and premium dark mode

- Enforced tenant isolation and Role-Based Access Control across all API routes

- Implemented secure profile avatar upload using multer and UUIDs

- Redesigned UI with a premium "Onyx & Gold" Charcoal dark mode

- Added Funnel Stage and Origin filters to Dashboard and User Detail pages

- Replaced "Referral" with "Indicação" across the platform and database

- Optimized Dockerfile and local environment setup for reliable deployments

- Fixed frontend syntax errors and improved KPI/Chart visualizations

components/DateRangePicker.tsx

@@ -27,21 +27,21 @@ export const DateRangePicker: React.FC<DateRangePickerProps> = ({ dateRange, onC
   };
 
   return (
-    <div className="flex items-center gap-2 bg-white border border-slate-200 px-3 py-2 rounded-lg shadow-sm hover:border-slate-300 transition-colors">
-      <Calendar size={16} className="text-slate-500 shrink-0" />
+    <div className="flex items-center gap-2 bg-white dark:bg-dark-bg border border-zinc-200 dark:border-dark-border px-3 py-2 rounded-lg shadow-sm hover:border-zinc-300 dark:hover:border-zinc-700 transition-colors">
+      <Calendar size={16} className="text-zinc-500 dark:text-dark-muted shrink-0" />
       <div className="flex items-center gap-2 text-sm">
         <input
           type="date"
           value={formatDateForInput(dateRange.start)}
           onChange={handleStartChange}
-          className="bg-transparent text-slate-700 font-medium outline-none cursor-pointer w-28 md:w-auto"
+          className="bg-transparent text-zinc-700 dark:text-zinc-200 font-medium outline-none cursor-pointer w-28 md:w-auto"
         />
-        <span className="text-slate-400">até</span>
+        <span className="text-zinc-400 dark:text-dark-muted">até</span>
         <input
           type="date"
           value={formatDateForInput(dateRange.end)}
           onChange={handleEndChange}
-          className="bg-transparent text-slate-700 font-medium outline-none cursor-pointer w-28 md:w-auto"
+          className="bg-transparent text-zinc-700 dark:text-zinc-200 font-medium outline-none cursor-pointer w-28 md:w-auto"
         />
       </div>
     </div>