chore: post-deployment cleanup and docs update

- Make AI routing rules DB-driven (read from system_configs, removed from config.py)
- Add translation quota tracking to LLM translation (OpenAIProvider)
- Add Alibaba MT ECS RAM role support (STS token, no AccessKey needed)
- Fix admin sidebar link for AI模型配置 page
- Fix Quota.vue API path (quotas → translation-quotas)
- Fix login auto-redirect to dashboard
- Add provider dropdown selects to AI routing config UI
- Clean up stale ai_provider_* system_configs records
- Remove OpencodeGo, Spark providers (code + DB)
- Update deploy config: nginx port 8000, systemd cwd

admin-frontend/src/views/Quota.vue

@@ -4,7 +4,7 @@
       <el-card shadow="never">
         <template #header>
           <div class="quota-header">
-            <span class="quota-version">{{ q.version === 'ecommerce' ? '电商版' : '通用版' }}</span>
+            <span class="quota-version">{{ { ecommerce: '电商版', general: '通用版', llm: 'AI模型翻译' }[q.version] || q.version }}</span>
             <el-tag size="small" v-if="q.description">{{ q.description }}</el-tag>
           </div>
         </template>