fix(ui): 9项端到端真实审计 — 修复记忆/技能/审计/工作区/MCP数据流断裂

基于 Tauri MCP 实机排查发现并修复：

1. VikingPanel: viking_ls('/') 返回0 → 改为 viking_ls('') 返回100条记忆
2. 技能列表: loadSkillsCatalog 静默失败 → 添加直接 invoke('skill_list') 回退
3. 审计日志: 面板读Gateway API无数据 → 回退读localStorage双源数据
4. 工作区: 浏览按钮无事件 → 接入prompt选择 + workspace_dir_stats 命令
5. MCP: 空列表无引导 → 添加配置文件路径提示
6. 新增 workspace_dir_stats Tauri 命令 (Rust)

排查确认正常的功能: 安全存储(OS Keyring✅), 心跳引擎(运行中✅),
定时任务(管道连通), Kernel(已初始化✅), SaaS relay模式

desktop/src-tauri/src/kernel_commands/mod.rs

@@ -17,6 +17,7 @@ pub mod orchestration;
 pub mod scheduled_task;
 pub mod skill;
 pub mod trigger;
+pub mod workspace;
 
 #[cfg(feature = "multi-agent")]
 pub mod a2a;

desktop/src-tauri/src/kernel_commands/workspace.rs

@@ -0,0 +1,43 @@
+//! Workspace directory statistics command
+
+use serde::Serialize;
+use std::path::Path;
+
+#[derive(Serialize)]
+pub struct DirStats {
+    pub file_count: u64,
+    pub total_size: u64,
+}
+
+/// Count files and total size in a directory (non-recursive, top-level only)
+#[tauri::command]
+pub async fn workspace_dir_stats(path: String) -> Result<DirStats, String> {
+    let dir = Path::new(&path);
+    if !dir.exists() {
+        return Ok(DirStats {
+            file_count: 0,
+            total_size: 0,
+        });
+    }
+    if !dir.is_dir() {
+        return Err(format!("{} is not a directory", path));
+    }
+
+    let mut file_count: u64 = 0;
+    let mut total_size: u64 = 0;
+
+    let entries = std::fs::read_dir(dir).map_err(|e| format!("Failed to read dir: {}", e))?;
+    for entry in entries.flatten() {
+        if let Ok(metadata) = entry.metadata() {
+            if metadata.is_file() {
+                file_count += 1;
+                total_size += metadata.len();
+            }
+        }
+    }
+
+    Ok(DirStats {
+        file_count,
+        total_size,
+    })
+}

desktop/src-tauri/src/lib.rs

@@ -323,6 +323,8 @@ pub fn run() {
             kernel_commands::trigger::trigger_update,
             kernel_commands::trigger::trigger_delete,
             kernel_commands::trigger::trigger_execute,
+            // Workspace commands
+            kernel_commands::workspace::workspace_dir_stats,
             // Approval management commands
             kernel_commands::approval::approval_list,
             kernel_commands::approval::approval_respond,