fix(widgets): add multi-database compatibility to all dashboard widgets

Replace SQLite-specific functions with database-agnostic expressions to support
  MySQL, SQLite, PostgreSQL, and SQL Server across all Filament dashboard widgets.

  - Fix strftime() date formatting in SubscriptionMetrics, RevenueMetrics, and TrialPerformance
  - Fix CAST AS REAL syntax in ChurnAnalysis widget
  - Add getDateFormatExpression() method for date function compatibility
  - Add getCastExpression() method for CAST syntax compatibility
  - Support MySQL/MariaDB, SQLite, PostgreSQL, and SQL Server drivers
  - Maintain identical functionality across all database types

  Fixes multiple SQLSTATE[42000] syntax errors when using MySQL/MariaDB databases.

app/Filament/Widgets/RevenueMetrics.php

@@ -92,9 +92,11 @@ class RevenueMetrics extends ChartWidget
 
     private function getMonthlyRevenueTrend(): array
     {
+        $dateFormat = $this->getDateFormatExpression();
+
         return Subscription::query()
             ->select(
-                DB::raw("strftime('%Y-%m', subscriptions.created_at) as month"),
+                DB::raw("{$dateFormat} as month"),
                 DB::raw('SUM(plans.price) as revenue')
             )
             ->join('plans', 'subscriptions.plan_id', '=', 'plans.id')
@@ -106,6 +108,19 @@ class RevenueMetrics extends ChartWidget
             ->toArray();
     }
 
+    private function getDateFormatExpression(): string
+    {
+        $connection = DB::connection()->getDriverName();
+
+        return match ($connection) {
+            'sqlite' => "strftime('%Y-%m', subscriptions.created_at)",
+            'mysql', 'mariadb' => "DATE_FORMAT(subscriptions.created_at, '%Y-%m')",
+            'pgsql' => "TO_CHAR(subscriptions.created_at, 'YYYY-MM')",
+            'sqlsrv' => "FORMAT(subscriptions.created_at, 'yyyy-MM')",
+            default => "DATE_FORMAT(subscriptions.created_at, '%Y-%m')", // fallback to MySQL format
+        };
+    }
+
     private function getMRRByProvider(): array
     {
         return Subscription::query()