feat: add config API and update ApkList to use configured tabs

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/download/ApkList.tsx

@@ -1,6 +1,6 @@
 'use client';
 
-import { useState } from 'react';
+import { useState, useEffect } from 'react';
 import useSWR from 'swr';
 import { type ApkEnvironment } from '@/lib/apk-parser';
 import ApkTable from './ApkTable';
@@ -22,16 +22,26 @@ interface ApkListProps {
   commitId: string;
 }
 
-const TABS: ApkEnvironment[] = ['dev', 'product', 'sandbox', 'other'];
-
 export default function ApkList({ project, version, commitId }: ApkListProps) {
+  const [configuredTabs, setConfiguredTabs] = useState<string[]>([]);
   const [activeTab, setActiveTab] = useState<ApkEnvironment>('product');
 
+  // Fetch config on mount
+  useEffect(() => {
+    fetch('/api/config')
+      .then(res => res.json())
+      .then(data => setConfiguredTabs(data.tabs))
+      .catch(() => setConfiguredTabs(['dev', 'sandbox'])); // fallback
+  }, []);
+
   const { data: apks, isLoading, error } = useSWR<Apk[]>(
     `/api/apks?project=${project}&version=${version}&commit=${commitId}`,
     fetcher
   );
 
+  // Build tabs: product -> configured -> other
+  const TABS: ApkEnvironment[] = ['product', ...configuredTabs.filter(t => t !== 'product' && t !== 'other') as ApkEnvironment[], 'other'];
+
   if (isLoading) {
     return (
       <div className="text-center py-8 text-gray-500">