Rename DB_SSLMODE env to DB_SSL_MODE and add DATABASE_URL fallback

The Laravel 13 config update made sslmode read DB_SSLMODE, which the
self-hosting examples set to require, breaking instances whose database
does not support SSL. Use DB_SSL_MODE instead so existing values are
ignored again, and fall back to DATABASE_URL when DB_URL is not set.

config/database.php

@@ -35,7 +35,7 @@ return [
 
         'sqlite' => [
             'driver' => 'sqlite',
-            'url' => env('DB_URL'),
+            'url' => env('DB_URL', env('DATABASE_URL')),
             'database' => env('DB_DATABASE', database_path('database.sqlite')),
             'prefix' => '',
             'foreign_key_constraints' => env('DB_FOREIGN_KEYS', true),
@@ -47,7 +47,7 @@ return [
 
         'pgsql' => [
             'driver' => 'pgsql',
-            'url' => env('DB_URL'),
+            'url' => env('DB_URL', env('DATABASE_URL')),
             'host' => env('DB_HOST', '127.0.0.1'),
             'port' => env('DB_PORT', '5432'),
             'database' => env('DB_DATABASE', 'forge'),
@@ -57,12 +57,12 @@ return [
             'prefix' => '',
             'prefix_indexes' => true,
             'search_path' => 'public',
-            'sslmode' => env('DB_SSLMODE', 'prefer'),
+            'sslmode' => env('DB_SSL_MODE', 'prefer'),
         ],
 
         'pgsql_test' => [
             'driver' => 'pgsql',
-            'url' => env('DB_URL'),
+            'url' => env('DB_URL', env('DATABASE_URL')),
             'host' => env('DB_TEST_HOST', '127.0.0.1'),
             'port' => env('DB_TEST_PORT', '5432'),
             'database' => env('DB_TEST_DATABASE', 'forge'),
@@ -72,12 +72,12 @@ return [
             'prefix' => '',
             'prefix_indexes' => true,
             'search_path' => 'public',
-            'sslmode' => env('DB_SSLMODE', 'prefer'),
+            'sslmode' => env('DB_SSL_MODE', 'prefer'),
         ],
 
         'sqlsrv' => [
             'driver' => 'sqlsrv',
-            'url' => env('DB_URL'),
+            'url' => env('DB_URL', env('DATABASE_URL')),
             'host' => env('DB_HOST', 'localhost'),
             'port' => env('DB_PORT', '1433'),
             'database' => env('DB_DATABASE', 'laravel'),