feat: Batch 5-9 — GrowthIntegration桥接、验证补全、死代码清理、Pipeline模板、Speech/Twitter真实实现

Batch 5 (P0): GrowthIntegration 接入 Tauri
- Kernel 新增 set_viking()/set_extraction_driver() 桥接 SqliteStorage
- 中间件链共享存储，MemoryExtractor 接入 LLM 驱动

Batch 6 (P1): 输入验证 + Heartbeat
- Relay 验证补全（stream 兼容检查、API key 格式校验）
- UUID 类型校验、SessionId 错误返回
- Heartbeat 默认开启 + 首次聊天自动初始化

Batch 7 (P2): 死代码清理
- zclaw-channels 整体移除（317 行）
- multi-agent 特性门控、admin 方法标注

Batch 8 (P2): Pipeline 模板
- PipelineMetadata 新增 annotations 字段
- pipeline_templates 命令 + 2 个示例模板
- fallback driver base_url 修复（doubao/qwen/deepseek 端点）

Batch 9 (P1): SpeechHand/TwitterHand 真实实现
- SpeechHand: tts_method 字段 + Browser TTS 前端集成 (Web Speech API)
- TwitterHand: 12 个 action 全部替换为 Twitter API v2 真实 HTTP 调用
- chatStore/useAutomationEvents 双路径 TTS 触发

desktop/src/lib/saas-client.ts

@@ -920,6 +920,12 @@ export class SaaSClient {
     return this.request('GET', '/api/v1/config/pull' + qs);
   }
 
+  // ==========================================================================
+  // Admin Panel API — Reserved for future admin UI (Next.js admin dashboard)
+  // These methods are not called by the desktop app but are kept as thin API
+  // wrappers for when the admin panel is built.
+  // ==========================================================================
+
   // --- Provider Management (Admin) ---
 
   /** List all providers */