feat: tambah API Key Desa Plus ke Settings panel dan proxy

- Tambah kolom API_KEY_DESA_PLUS di CONFIG_DEFINITIONS (ditampilkan sebagai password field)
- Proxy otomatis menyertakan X-API-Key header jika API key sudah dikonfigurasi

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

src/app.ts

@@ -1583,13 +1583,17 @@ export function createApp() {
     // ─── Desa Plus Proxy ───────────────────────────────────────────────────────
 
     .all('/api/proxy/desa-plus/*', async ({ request, set }) => {
-      const baseConfig = await prisma.appConfig.findUnique({ where: { key: 'URL_API_DESA_PLUS' } })
+      const [baseConfig, apiKeyConfig] = await Promise.all([
+        prisma.appConfig.findUnique({ where: { key: 'URL_API_DESA_PLUS' } }),
+        prisma.appConfig.findUnique({ where: { key: 'API_KEY_DESA_PLUS' } }),
+      ])
       if (!baseConfig?.value) { set.status = 503; return { error: 'URL_API_DESA_PLUS belum dikonfigurasi. Set di /dev → Settings.' } }
       const base = baseConfig.value.replace(/\/$/, '')
       const url = new URL(request.url)
       const upstream = `${base}${url.pathname.replace('/api/proxy/desa-plus', '')}${url.search}`
       const headers = new Headers(request.headers)
       headers.delete('host')
+      if (apiKeyConfig?.value) headers.set('X-API-Key', apiKeyConfig.value)
       try {
         const res = await fetch(upstream, { method: request.method, headers, body: request.method !== 'GET' && request.method !== 'HEAD' ? request.body : undefined })
         const contentType = res.headers.get('content-type') ?? 'application/json'