feat(database): default new Redis databases to the Valkey image

Change the standalone_redis image column default to
valkey/valkey:9-alpine. Existing databases keep their current image.
Update the API docs, OpenAPI specs and image helper text to name Valkey
as the default and redis:8 as the Redis example.

Also restyle the status badges and database image cards on the new
resource page.

database/migrations/2026_11_06_113843_set_valkey_as_standalone_redis_default_image.php

@@ -0,0 +1,25 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration
+{
+    /**
+     * Existing databases keep their image. Only new databases use Valkey.
+     */
+    public function up(): void
+    {
+        Schema::table('standalone_redis', function (Blueprint $table) {
+            $table->string('image')->default('valkey/valkey:9-alpine')->change();
+        });
+    }
+
+    public function down(): void
+    {
+        Schema::table('standalone_redis', function (Blueprint $table) {
+            $table->string('image')->default('redis:8')->change();
+        });
+    }
+};