fix(desktop): Tauri 端找碴验证 7 项修复 — 消息泄漏/UUID暴露/错误友好化

B15/B11: streamStore onAgentStream 添加 activeRunId 过滤，移除降级匹配，
hand/workflow 消息追加前验证 runId 归属；chatStore 切换/新建对话时
先 cancelStream 终止旧流；ChatArea hand-execution-complete 事件
添加 isStreaming 守卫

B4/B5: ChatArea 模型列表过滤 embedding 模型，provider 设为 undefined
隐藏 UUID

B2/B3: streamStore onError 添加 formatUserError 函数，将原始 JSON
错误转换为中文友好提示

B1: SuggestionChips onSelect 延迟调用 handleSend 自动发送建议

fix(runtime): test_util.rs with_error 添加 mut self，with_stream_chunks
移除多余 mut

fix(saas): lib.rs 添加 Result/SaasError re-export

crates/zclaw-runtime/src/test_util.rs

@@ -79,7 +79,7 @@ impl MockLlmDriver {
     }
 
     /// Queue an error response.
-    pub fn with_error(self, _error: &str) -> Self {
+    pub fn with_error(mut self, _error: &str) -> Self {
         self.push_response(CompletionResponse {
             content: vec![],
             model: "mock-model".to_string(),
@@ -97,7 +97,7 @@ impl MockLlmDriver {
     }
 
     /// Queue stream chunks for a streaming call.
-    pub fn with_stream_chunks(mut self, chunks: Vec<StreamChunk>) -> Self {
+    pub fn with_stream_chunks(self, chunks: Vec<StreamChunk>) -> Self {
         self.stream_chunks
             .lock()
             .expect("stream_chunks lock")

crates/zclaw-saas/src/lib.rs

@@ -28,3 +28,5 @@ pub mod telemetry;
 pub mod billing;
 pub mod industry;
 pub mod knowledge;
+
+pub use error::{SaasError, SaasError as Error, SaasResult as Result};