Unify all dropdowns on the custom Select component.

Replace every native <select> across the dashboard, admin pages, and
shared components with the custom Select used by the optional-service
version pickers, for consistent styling and mobile-safe anchoring. Add
a disabled prop to Select to cover the former read-only native cases.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/src/components/managed-database-config.tsx

@@ -4,6 +4,7 @@ import { useRef, useState } from 'react';
 import { Database, Eye, EyeOff, RefreshCw, AlertCircle } from 'lucide-react';
 import { toast } from 'react-toastify';
 import { useT } from '@/i18n/I18nProvider';
+import { Select } from '@/components/ui/select';
 import { ONE_GIB, minGiToFitFileBytes } from '@/lib/storage-utils';
 
 export type DatabaseEngine = 'postgresql' | 'mysql' | 'mariadb' | 'mongodb';
@@ -101,17 +102,17 @@ export function ManagedDatabaseConfig({
 
       <div>
         <label className="block text-sm font-medium text-gray-700 mb-1">{c.version}</label>
-        <select
-          className="input-field max-w-xs"
+        <Select
+          size="md"
+          className="max-w-xs"
+          ariaLabel={c.version}
           value={form.dbVersion}
-          onChange={(e) => onChange({ dbVersion: e.target.value })}
-        >
-          {versionOptions(form.databaseType).map((v) => (
-            <option key={v} value={v}>
-              {versionLabel(form.databaseType, v)}
-            </option>
-          ))}
-        </select>
+          onChange={(v) => onChange({ dbVersion: v })}
+          options={versionOptions(form.databaseType).map((v) => ({
+            value: v,
+            label: versionLabel(form.databaseType, v),
+          }))}
+        />
       </div>
 
       <div className="p-4 bg-blue-50/50 border border-blue-200 rounded-xl space-y-4">